Did a search, found some games but no list... Bear in mind I'm talking about games which utilize gravity as a main feature, such as Bombardiers Guild, Slingshot and Lunarcy. Other games with a gravity gimmick (i.e. Trism) don't count. Let's go!
Gravity Sling. The free version has in app purchases. There is also a deluxe version with all levels.
gravity sling is in my opinion the best gravity game out there. i really quite like it! it's addictive and really pretty!
Orbital. I recently bought this gem and have been playing it non stop. If you haven't already tried it, there is a lite version!
Hm... not really. I'm thinking more of games with multi-directional gravity, or objects that have their own levels of gravity. Implode and Perfect Balance just makes things fall downward... if we count them we'd be counting platformers too since when Mario jumps, he comes back down again Soosiz would be alright though.