Minecraft Version Changer provides a big list of Minecraft versions to choose from. It takes just seconds to change between versions. You can even generate a backup of your current jar file if you have any mods installed that you don't wan't to lose. Choose a version from the list, click on "Change" then let Minecraft Version Changer do the work for you.
What's new in this version:
+ 13w11a - Client and Server. Fx MVC no longer require http://mcvc.in to be online. (Now connecting to http://tunkdesign.com/)
+ Minecraft 1.5.2 - Client and Server.
+ 13w18a - Client and Server.
+ 13w12_ - Client.
+ Special information for the following versions; Demo, 2.0 - Blue, 2.0 - Red and 2.0 Purple
+ Debug output is now shown without setting debug to TRUE in mvc.properties.