The story of Prince of Tennis is almost a moot point. This series exists solely to have attractive guys play tennis against one another. I'm not saying it's a bad thing, though.
There is a TON of artwork from this series out there. This particular post is made up entirely of group shots and primarily features artwork from the anime.
If you're interested in checking out this series, the manga and anime are both available from Viz Media (although it looks like the anime version's release is on hold). The original manga ended a while back but a new manga series just recently started in Japan. If they in turn make a new anime series out of it, then there will be no shortage of artwork for years to come.
Image Archive (.zip): RS or MF