Up until recently, Amigakit had clockport adapters ($20-$30?) for use with Amiga 1000/500/2000. I always wondered if it would be worth hooking a Subway to it since I wasn't aware of any USB drivers for the 68000. Well, now there are (there was a thread about it recently here) and the clockport adapters are now sold out 
Looks like the 68000 can handle simple USB stuff like input devices and printing...
Subway with Poseidon drivers (via clockport) is a no-go on stock 68000, needs a 68020 or better. ANAIIS will work for limited scope of devices (keyboard, mouse, printer, maybe even flashdisk).
At least one A500 user with PPS040 have it running on Poseidon; USB comes as part of Ethernet bridge adapter so A500 can go online. Speed appx. 100KBps, limited by availabale clockport bandwidth (1Mbit).
I (and few other member of this forum) tried to reproduce the same scenario, but without any significant progress. It seems that GVP A530 has some nasty tricks in basic design which kills performance of bare machine when USB stack is initialized, too many concurrent CPU polls through clockport, very disappointing.
Getting Zorro2 passthrough sidecar is way to go for A500 expansion options. You can stick an accelerator aside (or on top of CPU, whatever)and still have a single free slot for non-DMA peripheral, like X-Surf NIC.
