Back-In-Time is a helper app for Time Machine that gives you more detailed access into--and more options for manipulating--backed-up data.
While Time Machine has an elegant built-in interface, it can be limiting for users who want more control and flexibility. Back-In-Time offers an interface similar to Time Machine's, but in an easy-to-browse, two-pane view that lets you access data from multiple Macs, get Quick Look previews (including comprehensive version history, date, and size info), and even drag and drop to recover individual files and folders. You can also compare two versions of the same file, with a graphical view of their differences. Back-In-Time lets you browse with multiple windows, restore entire disks (just as Time Machine does), and copy and restore data to any location, including attached disks.
Overall, this is an excellent complement to Time Machine and an especially useful app for anybody who works with multiple Macs or just wants more options for working with backed-up data.