Kevin,

Many States offer these. Unfortunately, many states will only sell those liens in bulk. Cuyahoga County (my county) will only sell them in batches of 500. Which means only REITs and GLS (Georgia Lien Services) are the only ones who can afford to buy them. Furthermore, some States require they be BID on. The BID winner, is the company that offers the repayment at the LOWEST interest rate. Usually around 3-5%. This is usually why savy investors will invest in things with a greater return.
Florida as I understand it will allow single tax lien purchases. I beleiev the payback to the lien holder is 2 years though, so again it's a matter of investment return.
Better to take a stock like Lucent and play the buy sell game with that stock. It's so cheap and volitile you can double your money if you watch it daily. Many folks use Tax Liens/Deeds as a way to aquire property, not investment on interest.

George