I talk to a lot of developers, see a lot of resumes, and give a fair deal of interviews. One of the biggest gaps I see is a lack of any extracurricular activities - i.e. work-related tasks not required by your current job. Empirically, I notice a direct relationship between a dev's technical confidence and the quality of their extra curriculars. Here are some ideas of good extra curriculars that won't just make your resume stick out, they'll make you a fundamentally better developer.
- Write a technical article (such as for www.codeProject.com, or any website in the Codezone community).
- Start your own blog
- Give an internal presentation to your company
- Mentor newer developers
- Help out with your companies technical interviews
- Get a certification
- Get a patent (obviously not feasible with most companies, but the larger ones may support it)
- Start an open-source project
- Attend a user group (for example, if you're in Chicago, consider attending the Chicago .Net User's Group)
- Participate in online forums, answering others questions (which goes great with having your own blog and writing articles)
- Make your own personal website
- Help your non-technical friends set up their own web sites.
No matter where you are, there's likely at least some of these you could do in your current job.