Path of Exile tools
This tool downloads all offers from trading forum on official website. You can easily search items for trade according to specified criterias.
Full list of quest rewards for all classes. You can plan what gems you get from quests.
This program counts statistics from your passive skills and equipment. You can easily plan build for your char.
It's a list of all the mods in the game based on the official item data page.
With this spreadsheet, you can calculate your character's DPS for a large variety of different skill, build and equipment combinations.
It takes your build / skill / support / gear info and shows the relative benefits of all mana related stats. It also shows the cost of raising your attack or cast speed.
It showing the experience penalty by area for your current level.