MultiMC 

MultiMC is a custom launcher that makes managing Minecraft easier by allowing you to have multiple installations of Minecraft at once. This means that you can have two different .minecraft folders each with it's own mods saves texture packs, etc. without having to waste your time fooling around with .bat files. It also allows you to easily install and remove mods without you even having to touch WinRAR or 7zip at all. This allows you to spend less time trying to get your mods to work and more time actually enjoying Minecraft. MultiMC also tries to detect when Minecraft crashes and tell you what happened and how to fix it.