Well I'll name some lesser knowns, that still contributed to the Amiga name.
US Gold (For all those sports games and Golden Axe port)
Ocean (More ports to Amiga, thanx to them.. Robocop to name a few)
Microprose (a pc to Amiga porter)
And for the better knowns
Interplay for battle chess (going under soon?)
Maxis (what can i say SimCity and Simcity 2000 were flawless on the Amiga)
Cinemaware[/url] (Still kickin I hear)