The Last.fm download any track hack
1. Install LiveHTTPHeaders plugin for Firefox
2. Install a download manager (e.g. DownThemAll! plugin for Firefox)
3. Find any song on Last.fm and wait for the page to load (its only really worth doing on full tracks)
4. Firefox > Tools > Live HTTP Headers
5. Press play, then stop on the last.fm player
6. In the header log you should see a link similar to this, select and copy it.
http://s1.last.fm/anon/313334524/aa31857106858cd481adc4254a93a9dc/248/0010016013/25ea725301cd2b9a1ba49c92ccda66fe/1224246011/44/142211215/fod.mp3
7. Start the download in your manager with the link found, you may need to delete the last invisible return character at the end of the URL.
N.B. This works for any song and you should get between 128 and 320, remember to delete it after and use the buy link if you like it.