Absolutely you should mention them. The purpose of a CV or job application is to make you stand out from the herd and give the potential employer a reason to pick you (or at least bring you in for an interview) instead of any of the other applicants.
Depending on the size of the company and the internship program you may be up against tens, hundreds, maybe thousands of other applicants. All of those are likely to be at a similar stage in their studies to you. All of them will have done similar courses and similar labs. Inevitably your CVs and applications are going to be similar.
But only YOU have done YOUR projects - they're something concrete that sets you apart. It shows your particular interests and how you apply yourself. Doing an optional that few students attempt (and I assume less do successfully) shows that you're serious and not just doing what you need to get by.
This is exactly the sort of stuff that good employers will be looking for; it's the stuff that sets your application apart from the 10, 20, 50 other similar applications the hiring manager has read today. It's the stuff that gets you in the door.
Also, to shamelessly steal from sevensevens' answer, you should seriously consider using GitHub or a similar online repository if you're not already, both as a way of storing your work safely and to build a portfolio which can bolster your applications.