Many online players do not take nightly session notes as to how much they are winning and losing. There are tracking devices such as Pokertracker, to break down those huge amounts of hand histories and help you plug those holes in your game.

For the tournament player who doesn't have Pokertracker and wants to know if that "new" opponent that is re-raising his blind steals is a donkey or a shark, take a look at Offical Poker Rankings dot com.

You can use it for any of the major sites such as PokerStars, Full Tilt, and Party Poker to find your personal log of triumphs and defeats. It can be a great tool down the stretch of a tourney where the players may not be as familiar to you as in a cash game. Finding out if the Pirate icon'd guy has won his last three $109 Multi-table tourneys, or is he just blowing hot air and ripe for loosening his chips into your stack.

Here's a little detail from the site itself:

Poker Rankings
Official Poker Rankings (OPR) is an online poker rankings site with tournament results, tournament poker rankings and poker player rankings for online poker players. Official Poker Rankings (OPR) have MTT and SNG poker tournament results and online poker player results, summaries and statistics with all information including player alias, prizes, profit, ROI, ITM and exact finish.

Keep track of your poker tournament results
Keep track of your online poker tournament results and discover how you and your opponents, friends, colleges and family are performing playing online poker. Learn who the poker-sharks are, visit the pokerrooms and watch all the best online poker players play.

Realtime poker rankings and results
All poker rankings are updated and new players and tournaments are added to OPR every hour 24/7.