Summer Internships - The Good, and the Bad?

loquacious d asks: "This has been a spectacular summer for open-source student internships. Google funded a huge variety of open-source projects through the Summer of Code, including GCC-CIL and other improvements to Mono, new features and fixes for Gaim, and even new packages for Common Lisp. Joel Spolsky at Fog Creek hired four interns to produce a highly modified version of VNC called Fog Creek Copilot, and Paul Graham's new venture capital firm Y Combinator helped students create their own tech companies. What internships did people enjoy this summer, and which ones didn't work out so well? Which ones would you recommend to next year's applicants, and which should they avoid?"