I set up 2 accounts, one on Ebay.co.uk and one on Ebay.com - I use the UK one for football programmes and things that I sell to the UK (Usually because they are heavy) and occasionally some chips (UK ones mostly), and use Ebay.com for most of my chips, especially US ones.

You need 2 different email addresses (and probably 2 different credit cards) but apart from that it is all ok and within Ebay rules.

Jason