Many expansion boxes for the Amiga 500 will work on the 1000... It won't be pretty, since it will be backwards (the a1000 slot is on the other side from the 500) and a bit off the ground... You might have to put a book under it..
Depending on your skill with a soldering iron... there's a hack on aminet that lets you use one A2000 style card on a 500 or a 1000. I used a commercial 2-slot box with a CBM ram card and a Trumpcard SCSI hard drive on my 1000 for years.
I think I saw an IDE hack for the 500 on aminet.. that might work in a 1000..
Software wise, you'd probably want a rom card in the 1000, unless you want to use a kickstart floppy..
