Hidden Start is a great utility that is essential for when you are using Windows Vista. Two key use cases are the launching of commandline utilities in the background, and the quiet use of unsigned executables that normally trigger a security warning and confirmation dialog.
In the latter case, I've made use of HStart together with UMPCScrollbar so that UMPCScrollbar can be included in the Startup group without a warning at each logon.
I also use this tool with Exact Audio Copy, so ensuring that the commandline Flac encoder can be launched in the background without a console.
HStart is a free (as in beer) download, and has 32-bit and 64-bit flavours.