The website 'Amiga Flame' put together such a list, although as Korodny points out most of these games were only given permission to be downloaded from a particular website (the list points out which ones).
http://www.amigaflame.com/amiretro.htm
I don't know how up to date it is - the 'news' section of the website was last updated two years ago.
Interestingly, I thought that Ami Sector One had fully merged with Back To The Roots before it shut down, but there are many games listed here which were not transferred to Back To The Roots, including (it seems) most or all of Electronic Arts' back catalogue. Don't know if that's because EA had a change of heart, or what...