Shortcut to set screen resolution
You can use a commandline tool like QRes.exe and create a shortcut to it that passes the resolution you want. So one shortcut per resolution.
Place QRes.exe wherever you like, and place the shortcut on the desktop, then edit the shortcut to include the resolution.
It will look something like this:
"C:\Path\To\QRes.exe" /x:800 /y:600
(this works only on windows btw, but something similar could probably be found for most OS's)