Gemplanner
Auto-plan gem acquisition for your campaign.
Paste your Path of Building code (or select a pre-defined guide). The Gemplanner shows which quest rewards each skill gem and which vendor sells it, from Act 1 to Act 10, so you never level past a gem you need.
Predefined leveling guides included.
vendor
Also worth exploring: TraXile
A desktop app that reads your Client.txt while you play and turns every area you enter and every death into statistics on your Path of Exile progress.