The best use I've found for LastFM (other than in a general stat-head way) is somebody's clever mashup, using Yahoo's pipe tool, of LastFM and Youtube. The page searches for youtube videos based on recently played tracks. Lots of false hits, and plenty of unwanted results, but some gems too.
Like...
1966-ish John Lee Hooker sings Boom Boom.
John Lee Hooker sings Hobo Blues at the 1965 American Folk Blues Fest
John Lee Hooker and Van Morrison sing, Gloria.
Bonus - footage from the Band's farewell concert, The Last Waltz featuring Van Morrison and his foot kicks. Straight out of the 70s.
If you like JLH and you haven't listened to Sirius Satellite Radio Channel 74, you haven't lived. If you love the blues (the way I do), it's worth the price of a sat radio and the subscription.
JLH is one of my all-time faves, I had the pleasure of seeing him perform live a couple times. Great presence on the stage.
I also love the blues, and have been collecting it for a long, long time, but I do not listen to the radio. Just don't spend much time on the road, and isn't it hard to get a Satellite radio to work in your house?
Don't know, it came in the new Ford and I listen to it on my commute (30 miles in NYC traffic).