Windows Vista/Windows 7: If you're running multiple operating systems—and if you weren't before the release of Windows 7 you most likely are now—EasyBCD is a simple application for tweaking your bootloader through a clean GUI and well-detailed prompts.
With EasyBCD you can edit the names of entries, add and remove entries onto the bootloader menu, change the timeout on the bootloader selection menu, and tweak boot-related items like enabling PAE mode or run with the debug process enabled. EasyBCD includes support for adding Windows, Linux, Mac, NeoGrub, and WinPE loaders.
If this is your first time tinkering with a bootloader, EasyBCD makes the process fairly simple. By default the application is in basic mode instead of expert mode—in expert mode it won't prompt you if you're doing something that could be difficult to undo. For additional information you can visit the EasyBCD wiki.
Note: Although we didn't have any problems doing some minor tweaks on our test machine with the current public release of EasyBCD, if you're doing any heavy overhauling you'll want to play it safe and download the beta release. The beta officially supports Windows 7 and is available here.
Have a boot-related trick or tweak? Let's hear about it in the comments. EasyBCD is freeware and works with Windows Vista and up.