A must have for any rooted phone! Almost EVERY rooted applications needs BusyBox to perform their magic, if you have a rooted phone then you need BusyBox.
Pro version contains Backup feature (for safer installs), uninstall feature, Advance Smart install feature, the ability to hand pick the applets you want, safety check for missing applets on start, and better overall support. The pro version will receive more frequent updates than the free version will.
BusyBox is a software application that provides many standard Unix tools, much like the larger (but more capable) GNU Core Utilities. BusyBox is designed to be a small executable for use with the Linux kernel, which makes it ideal for use with embedded devices. It has been self-dubbed "The Swiss Army Knife of Embedded Linux".
Your device may require rooting to use this app, please refer to Root Your Android for instructions.