Last year, one way I collaborated with a fellow mentee and our mentor was via a professional blog. (Click here to view it.) We didn't post too many entries, but it did serve as a place to host our live blogging sessions (via CoveritLive), our podcasts of professional conversations (via Skype), and more recently, "help" videos of relevant Web 2.0 apps. Consider keeping a professional blog with your mentor/mentee or simply on your own. It's a great way to show off all the work you accomplish throughout the year.