There's already a thread for my hack so it will not be listed here.
Advance Wars Project by XenesisXenon
This one hasn't been released yet, but it looks promising with all the new features and units.
AW2 Balance Hack by XenesisXenon (again)
This is an attempt to balance all the COs and units in AW2. A noble effort, but I have to ask, is allowing B-Copters to carry infantry at all balanced? Meh. At least Grit isn't broken anymore.
Ember Hack by RadioShadow
This just adds a new CO and a few new maps. Not really that interesting IMO, but it does demonstrate that custom COs can be done.
The Grimm Hack by XenesisXenon (AGAIN)
This adds Grimm to AW2 with all his stats and even his theme song intact. Very interesting if you want to challenge the AW2 War Room with Grimm.
Xen's War Room Remix by XenesisXenon (duh)
Basically just some VS and Campaign maps made into War Room maps. See, this one was made before it was possible to edit anything other than unit positions and text.
War Room Remix 2 by XenesisXenon
Click that link. Now.