A lot of the "mashups" (a web application combing data from more than one source) I see only cover San Francisco or California or maybe just a few major metro areas, but here's one that includes data on Knoxville -- and it's useful too.
Vision 20/20 has created a nationwide sexual offender database/map mashup.
Go to the map search and enter Knoxville for city and TN for state. You might be surprised.
The company, which says it is committed to "Peace of Mind" products, frames this one around:
There are 650,000 registered sex offenders in America - and that number grows by about 25,000 every year. Wouldn't you like to know if any of them are living in your neighborhood?