There was a discussion about this on one of the soundclick forums recently. You can get daily stats on the hits to your page, and the individual songs, plus you can check out how they're doing in the charts.
The way I understand it, only your most popular song will appear in the charts, so even if you have 3, 4 or 5 songs that are gettting lots of play, only the top song will show in the charts. They do this so that a few bands don't dominate the charts; everyone gets one good shot. I had a song in the charts and deleted it to post a new version, and one of my other songs showed up in the charts.
The charts are fun to keep track of, nice to se how many folks are listening.