Each student is entirely responsible for finding a thesis topic and supervisor. While many people will be willing to help you, the final responsibility is yours alone.
Even if you haven't been involved in a research group where you can do your thesis, it still isn't that hard to find a thesis. If you already have a very specific topic in mind, you may have to be flexible and talk to many faculty and staff to find one interested in supervising you, so start early.
- You may have done a project in a laboratory subject which you wish to extend, or you may have done well in a subject which needs a lab or lecture demo developed. If so, talk to the appropriate faculty or staff members.
- Scan the technical journals.
- Network! Talk to your faculty advisor and any others you know for leads, and to develop and define your technical interest. Ask PhD students to recommend faculty.
- Browse the Research Supervisors list and MEng Thesis Research Opportunities in CSAIL, look at research group websites and then talk to members of research groups.
- Attend the many colloquia and seminars held by research labs and the Department. Every Fall each Graduate Area has an Open House -- be sure to attend those that might interest you.
- Narrow your scope to one or two specific research areas, and see faculty and staff in those areas. Skim their recent papers, then ask them what projects they need done, and who else might have suitable research available in the same area.
- Look at recent EECS theses in MIT DSpace. You will often find definite suggestions in such theses for additional work that needs to be done. If you get stuck, go back to your academic advisor and talk things out again, choosing a different field with new people to contact.
As soon as you have reached a meeting of minds with a supervisor, start work on a thesis proposal to get your topic defined and formalized.