Windows Sysinternals has released a new tool that is going to be used a lot by administrators everywhere: ShellRunAs.exe
ShellRunAs is similar to the runas command in Windows XP/Vista, but adds a context menu if you right click an executable file. This is invaluable to administrators, as most admin's have an additional account for administrative tasks.
ShellRunas works on Windows XP, Windows Server 2003, Windows Vista, and Windows Server 2008.