Relaunch saves you time by taking Snapshots of which applications you are using, and starts them back up for you. Think of it as a launcher on steroids that lets you switch between work contexts with one click. It's smart too! As well as starting groups of applications it also knows which documents you were working on in 30 popular applications and loads those up for you as well.
Relaunch sits in the Mac menu bar so it's always there - you can save and launch Snapshots on demand but Relaunch also features a ridiculously simple to use Auto-Snapshot mode. This sits in the background, periodically remembering what you have open. Should you need to reboot or suffer a power outage Relaunch will offer the option to start everything back up for you when you next login.