I just can't stand those site you have to spend 30 seconds just to find the goddamn download link, which is usually very well hidden so you will read all ads. But yeah dropbox is nice, although any site supporting direct link to the mp3:s are fine too i guess. I just listen to mp3:s/wav:s with embedded quicktime player, if I want to download the files I just use the firefox plugin Download Helper (works on streaming soundclick stuff too).
Main reason I like dropbox is the great drag and drop UI and syncing files between different computers works really good.