From Johanna Franklin of Carnegie Mellon University:
(She was a Summer Research Fellow at Carnegie Mellon University.)
This program is limited to CMU students. Each participant receives a stipend comparable to most REU stipends and spends 10 weeks doing research in an area of his or her choice with a faculty advisor. To apply, you need to submit a project proposal with a faculty member.
I functioned very independently during this program. Some people use these fellowships to continue work that they've been doing in a certain professor's lab or on a preexisting research project, but I started work on my honors thesis instead.
The program itself is structured very loosely. There were, I think, a total of three social events, and since all of us were off working in different departments, we didn't see each other much unless we knew each other to begin with. Still, if your college has a program like this and you have a specific professor you want to do research with, this is a great way to do it.