I recently bought myself a GB Micro, and I've been obsessively buying any games that take my fancy.  Does anyone have any recommendations of lesser-known games that are actually quite good?  I had an original GBA and an SP, so I know all about your Yoshi's Islands/Advance Wars/Minish Caps/Superstar Sagas etc.

For example, I read some reviews on a game I hadn't heard of called Lady Sia, checked out some Youtube clips, bought it for £3 and I think it's great.  Same goes for Go! Go! Beckham!, which has absolutely no right to be a good game, yet somehow is. 

Suggestions from any genre would be appreciated.

I'm playing Mother 3 (+Tomato's translation patch) right now, you need some 'extra' hardware for this to work though.

Wario Ware: Twisted, absolute fun

well you could get a DS  whoops wrong thread!

Anyway its nice to hear someone enjoying retro 2D gaming and the GBA is one of the best places for it but before we can recommend you some games we need to know what you already have? Update your collection so we can see what GBA games you already have.

In regards to your question i'd recommend:

Contra Advance: The Alien Wars EX	F-Zero: GP Legend	F-Zero: Maximum Velocity	Gradius Galaxies
Mario Kart: Super Circuit	Metroid Fusion	Metroid: Zero Mission	The Legend of Zelda: A Link to the Past
The Legend of Zelda: The Minish Cap

Some of these games may not be for everyone but try

Fire Emblem
Fire Emblem: The Sacred Stones
Road Trip: Shifting Gears
The Final Fantasy Remakes
Megaman Zero 1-4
Sonic Advance 1-3
Pokémon Emerald
The Super Mario Advance games 1-4
Tactics Orge
Riveria
Boktai
Golden Sun
Golden Sun: The Lost Age
Drill Dozer

Metroid Fusion, if you haven't already bought it.

I was being a bit sneaky by not listing what I have as I'm after more unprompted recommendations on some of the stranger titles I've bought but not yet played :). 

Ok, the games I have are as follows:

Sonic Advance 1-3, Donkey Kong Country 1-3, Denki Blocks, Metal Slug, Go! Go! Beckham!, Namco Museum, Yoshi's Island, Columns Crown, F-Zero Maximum Velocity, Finding Nemo (bought for my nephew's birthday but cynically retained after I played it), Chu Chu Rocket, Sonic Pinball Party, Mario Golf, Mario Tennis, Kuru Kuru Kururin, Astro Boy, Gunstar Heroes, Lady Sia, Wade Hixton's Counter Punch, Hajime No Ippo, Sega Arcade Gallery, Tony Hawks 2,  Iridion 2, Spyro Eternal Night, Klonoa, Klonoa 2, Rayman 3, Mario Advance 2, Mario Advance 3, Mario Advance 4,Wario Ware, Super Monkey Ball Jr, Game & Watch Gallery 4, Ninja Cop, Final Fight One, Zelda a Link to the Past, Zelda Minish Cap, Mario Kart. 

Looking into (i.e bidding on): TMNT, Metroid Fusion, FF Tactics, Tactics Ogre, Wario land 4, Mario Vs Donkey Kong, Gradius Advance, Kirby Nightmare in Dreamland, Splinter Cell, Kirby & the Amazing Mirror, Mario Bros NES Classic.

Games I'm looking patiently waiting to appear on Ebay unboxed:

asssssssssssssssssssssssssssssssssssddddddddddddddddddddddddddddddddddsadfafsl;kaFire emblem, Minish Cap I'd recommend. Also, try some lesser known rpgs like Breath of Fire and that Squeenix Mana rpg.

Mario & Luigi: Superstar Saga
Kirby Nightmare in Dream Land
Kirby & the Amazing Mirror
Metriod Zero mission
Metroid Fusion
Advance wars
Advance wars: Black Hole Rising
Final Fantasy Tactics
Kingdom Hearts: Chain of Memories
Ecks vs Sever
Ballistic:Ecks vs Sever

The Ecks vs Sever movie was bad but the two games are solid doom clones.

More recommended GBA games can be found here:

http://www.neogaf.com/forum/showthread.php?t=316510

That link is an absolute treasure trove!  Thanks.