Interactive Trackers
You should be able to hover over the "Trackers" link to popup a menu, instead of having to visit this page. If not, you may have Javascript disabled, or be using an older browser.
These require an account, in order to save the data you enter.
Market Tracker
Record items you put up for sale (per-server and market!), and record if and when they actually sell. You can search your selling history to see how much you've sold items for in the past.
Eternal Harvest Tracker
Helps you keep track of which monsters' souls you've captured (instead of having to rummage through 20+ soul stones in your inventory).