It was basically a 'Pre Xbox.'  Microsoft worked with Sega on it, and some of the same team was used on the Xbox.  So basically, like the PS1 is the PS3's grandparent, that Sega Dreamcast, is sort of like the Xbox 360's grandparent. 

(I know, different companies, and officially the same gen, but I think the Dreamcast inpiried the Xbox.)

Well, I was going to list a few games but it looks like everyone has that covered.  It was a good system for the time.  It was a shame that it had to end like that since Sega seemed to be finally coming back to their true form.  They made some emphasis on online gaming, had bad ass sport games, decent 3rd party support (mainly from Capcom, Power Stone, Marvel vs Capcom), etc...  Some might not like the controller.  It was bulky but compared to the first Xbox controller it was way better.  The first Xbox controller before they shrunk it down was far worse than DC controller.  Interesting how I played most of the games mention on the GCN.  Seems like a lot of good DC games got ported to the GCN.

Ah i remeber the 1st day i got the dreamcast. felt like a little kid it was an awesome feeling.

it offered so much gameplay it was utter fab. back then the cheapest PC was like £600 and with a dreamcast you could browse online and have a dedicated email adress @dreamcast.co.uk.

memory card vmu was also unique, had an lcd screen with a conrol pad and buttons on it, you could play mini games on it, theres to much to list.

dreamcast had a sort of facebook built into the dreamkey browser called dreamarena the chat rooms and messege boards were always fun to use, there was also another title that came out it was called planetring kinda like an online multiplayer minigame compilation where your avatar runs around a globe looking for games.

on top of that all the emulator disks that was availiable, the ability to play backup games without chipping not to mention the brilliance of phantasy star online.

Shenmue, Sonic adventure, Skies of arcadia, Evolution and etc.

I won't even have bought the DC if it weren't for Shenmue that game alone sold me to buy DC.

It also has this poly thing forgot the name lol, where you insert it on your controller that acts as a memory card and you can play some games on that aswell.The first console to feature online. Phantasy star? The DC has lot's of great potential it sad it was killed off early.

Soul Calibur and Shenmue...Maybe Code Veronica ...and not much else

Have you played Soul Calibur on the XBLA or Soul Calibur 2 on the PS2,GC, or Xbox?  Well, the original was released right when the Dreamcast launched (within a few weeks, anyway) and it looked as good as the sequel.  Hell, some of the exact same animations were used.  Now, this was in 1999 when the graphical standard was the N64 and PS1.  It was the first glimpse into the future.  But I'll go on......

-The Controller:  Felt great and worked like a dream.  Those Analog Triggers that we love the 360 for were on the Dreamcast controller, first.  There was also two slots built into it.  You could plug in a "rumble pak" for force feedback, a microphone for voice control (and even communication!), and the VMU--it allowed you to take your saves with you and play mini games based on full games.  Plus, you could look at your controller and get stats, call football plays, etc. 

-The Console:  Featured a built in clock that tracked the date and everything.  A game like Seaman would tell you what day it was, who's birthday it was, how old you were, and everything.  It was used very well.  Before that, systems like the PS1 and N64 didn't include those in their design.  There was also the built in modem.  People could play games like Quake 3 vs PC owners.  That's rare, even today.  The Dreamcast was doing it way back when.

-Some even say that the Dreamcast had the first mass market motion controls.  I've never owned Sega Bass Fishing (I think that's the game) or Samba De' Amigo but these were the culprits.  Look them up if you're interested.

-And most importantly, The Library:  Video games are always evolving and improving so the games that were good then aren't impressive now.  Plus, pretty much every single Dreamcast game that was worth a damn got ported to the PS2, Gamecube, PSP, and Xbox (and the few that didn't got sequels that made the original game forgettable).  But when the PS2--possibly the greatest system ever--was released, the Dreamcast's library was leagues better.  While PS2 owners (myself included) only had games like Tekken Tag and Onimusha (good but not great), Dreamcast gamers were feasting on back-to-back fresh, amazing experiences that were ahead of their time.  My PS2 hardly got any play until the very end of 2001.  

-Basically, it was my first foray into Sega territory and the only time I feel that Sega did everything right.

• Shenmue (a game so detailed that you could go into any house and look in the drawers in the dresser)
• Crazy Taxi
• Grandia 2 and Skies of Arcadia--two of the best RPG's you could hope to find at the time
• Jet Grind Radio (Jet Set Radio) one of the first cell-shaded games, ever
• Quake 3-online vs PC gamers
• Space Channel 5 -one of the best music games ever, at the time
• Seaman -a game that let you talk to a virtual creature that would talk back
• Soul Calibur -considered for a long time as possibly the best fighting game ever
• Phantasy Star Online -an online RPG--ON CONSOLES?
• Resident Evil -Was still a big deal and every game in the series was released for the console (Code Veronica was exclusive for a long time--this was the REAL RE3
• Street Fighter Alpha 3/Marvel vs. Capcom 2/Street Fighter 3/ Mortal Kombat/ Virtua Fighter/ Powerstone/etc.  Made this THE console of choice for fighting game fans (was the best--sometimes the ONLY console for these games for quite a while)
• Perfect or better than perfect ports of Arcade games at a time when Arcades were still somewhat important
• Graphics that were so far beyond the competition that it was scary.

It was an exciting time and it was great to be a part of it.  A lot of the games have lost there luster but like someone said, you had to be there.  A lot of the things you take for granted now were brand new, then.  And for a couple of years, the Dreamcast was the best place to be if you were a gamer.

It was a pretty good piece of hardware, but as I said, the past consoles from Sega were the ones that gave a mistrust to the Dreamcast on the developer's side and the potential got wasted.  

Shenmue, Soul Calibur, Code Veronica, etc, but also if you were into sports games Dreamcast is where the 2K sports series started. NFL 2K and NBA 2K games were the best football and basketball games around. These series were exclusive to Dreamcast for a while. Dreamcast had so many good games in such a short amount of time it was awesome if you had a Dreamcast at that time.

Never knew of it until I met the internet .

The Dreamcast was a console that had a lot of quality and/or original titles that were released in a very short period of time; and was pushed out of the market by a console which had very few good or original titles released (at that point in its life).

The net effect of this situation is to give the Dreamcast a mythical quality as an amazing system, and that it was unfairly treated within the market; whereas the reality was that poor performance by Sega with the Saturn, 32X, and Sega CD ruined their relationship with publishers and consumers and led to the early (and unfortunate) end to the Dreamcast.