The shmups category really needs the games "Perfect Cherry Blossom", "Imperishable Night", and "Embodiment of Scarlet Devil". These games by Japanese creator ZUN, pretty much created a new subgenre in the shmup field; the "curtain fire" or "bullet hell" style of playing.
You might have to do some localization work to get these games into English (not much more than a few text cutscenes), but if any English site would be carrying these games, Manifesto would be it.
While I agree that those games should be here and that they're great games (especially Shoot the Bullet), I've two notes -- one is that I doubt ZUN speaks English, and his games have not been translated into English, nor do they even have English installers -- so getting his games here might be difficult, as it'd require first translating his games (they're playable even if you don't know Japanese, but the menus and what story there is is all in Japanese, there's more story and text than you think in those games), and the second is that I don't believe he really created that genre (danmaku games are a little older than his games), though he's certainly by far the best developer in that genre.