I've put together my genie list of the best online poker tools I have found in the market. I will add more useful things as I find them but this is a really good starting point:

Odds Calculator
These help you see the probability of certain hands winning the round while you are playing in a game. It can also be used to help improve your game by testing your ability to read the odds while learning. Have a look at the one from pokerstove

Tournament Clock If you fancy hosting your own tournaments at home then you need a poker clock to run on your PC in the background to tell you when to change the blinds. The best one I've found is this one called the holdem poker tournament clock

Coming soon... Poker Genie branded spreadsheets to keep track of your games, a Poker Genie beginners card to print out and use in your own hosted poker games... and more..