I've had an account on Last.fm for more than 3 years and liked it on the spot. I love to explore new music, discover new artists, listen to streaming radio (that is, until it was free) and especially scrobbling the music I listen!
The geek in me simply freaks out seeing the amount of stats you can get from your Last.fm "scrobbled" data: the music I listened the most this week? Last month? What is my favorite Porcupine Tree song? In fact there's also lot of external services that offer awesome visualizations of your data.
This was great up to the day when I decided to put my whole music collection on the Windows Home Server and listen to it via the built in UPnP media sharing in Windows Media Player. That day I discovered that the Windows Media Player plug-in doesn't scrobble songs on network shares! It doesn't work, neither from an SMB shared folder, nor directly through UPnP sharing (which in fact is HTTP streaming).
