If you're planning on doing anything ROM/Kernel related, install a recovery you're sure you're gonna stick with, backup your default rom (right after installing the custom recovery), and read the fucking manuals (and forums.), look up before doing anything.

Otherwise, https://www.cerberusapp.com/ .
ROM Toolbox Pro is really enjoyable, if you have a custom ROM.
Also, Siyah's dual boot functions are hardcore m8 B].

EDIT: Buy the official facecase if you're wearing jeans. Just saying.