After seeing Miguel's post about the Navigation features of Monodevelop, I updated my Monodevelop version to 2.4 and I couldn't agree more with Miguel's opinion: Navigate To is the best feature of Monodevelop. It is awesome!!
You remember the type you want to work with, press Command-. (I'm using OS X), type part of its name (Monodvelop guys did an wonderful job about how little you have to type to find it) and voilà, your type is open and ready to edit!
See more features of Monodevelop here.