The Amiga Research OS tries to rewrite a platform independant replacement for Amiga OS

Catweasel is a universal floppy disk controller that uses unmodified PC diskdrives. The Catweasel can handle nearly any disk format. You can read all PC-formats (180k up to 1440k), Amiga DD and HD, Atari disks, Macintosh 720k, 800k, 1440k (DD,GCR,HD), Commodore C64 and C128 disks and many more...

Per Olofsson has made a number of screenshots of UAE running all sorts of programs.

Check out the UAE Developers meeting pages (September '97).

The ADF file format is explained in Laurent Clevy's ADF (Amiga Disk File) format FAQ

Check out the XT-Power Amiga Page, which is styled like an Amiga workbench, using Javascript.