Simply state which developers you believe should be more successful and well known amongst gamers. As in having more acclaim then they currently do and sales of their games. 

My picks are …

Starbreeze, makers of the Darkness and Riddick games.  Which I believe should have been more successful since they are outstanding devs. 

Fromsoftware, they have developed some really great games like the King’s Field series and more recently Demons’s Souls.

Intelligent Systems, makers of the incredibly addictive Fire emblem series and Advance wars. This developer certainly deserves bigger sales and more recognition.

Well those are my choices feel free to add some developers of your own or disagree with my choices, hence the real purpose of this thread is to give lesser known game devs some attention.         

Platinum/Clover is my choice:

While I haven't played the likes of Vanquish and God Hand, there is no doubt in my mind that the likes of Viewtiful Joe, Okami and such deserved more sales.

Wayforward - Contra 4, Lit, Shantae, A Boy & His Blob (Wii), Sigma Star Saga.  Good developer that should be given more serious projects and less shovelware.

Grasshopper -  No More Heroes, Killer 7, Fatal Frame IV.  I think they're 2-3 games away from being a major player.

I also agree with Starbreeze, Platinum games, and Intelligent Systems.

Fromsoftware and Intelligent Systems are two great choices!

All great picks so far. Before I would have said GRIN, but they're gone...

Anyways, I think most of the first party developers like Bungie or Naughty Dog don't get the recognition they deserve. Most people always say things like "Their games are overrated" or something like that... Well excuse me,  but last time I checked they're still mostly small teams that still manage to make amazing things. Give credit where credit is due is what I like to say!

Also, let's not forget Ubisoft Montréal. The best Ubi out there!

MercurySteam - Jericho was a decent B-game with some really twisted environment and boss designs. I knew they had a true AAA game in them, and I'm pleased as punch that they pulled it off with Castlevania: Lords of Shadow. I'm not so pleased with the sales so far. Buy it!

Omega Force - All of their games are just fun. I don't recall seeing a single one of them break a Metacritic average of 70. "HURRRR DYNASTY WARRIORS IS OLD AND TIRED!" No, you are old and tired!

And I'll second (or third) From Software. Demon's Souls gives me hope they might just break out one day. Hey! Maybe if they make an Armored Core strategy RPG to replace the raped and burned corpse of Front Mission! (It would sell like ass, but I want it. Baaaaad.)

The Phoenix Wright people!

Infinity Ward and Treyarch

*trollface*

Cyberconnect2 - I so wish that they could put that Naruto:UNS engine to use on a quality IP.