New York came up with a creative approach last week to snagging Amazon.com and other online retailers with affiliate programs.
The gist is that affiliates an online vendor has in a state (people who they pay a commission to for referring business to the vendor's web site - Amazon.com has thousands all over the country) count as a physical presence in the state. Overstock.com actually suspended their referral program in New York because of this.
Here's a later story http://www.news.com/8301-10784_3-9944934-7.html?part=rss&subj=news&tag=2547-1_3-0-5
All credit to NY for coming up with an interesting approach. This should be interesting.