Ask HN: What kind of things do you say about projects when interviewing?

When you talk about previous projects during an interview what kind of things do you say to make it informative and interesting?

For example (I'm a student), I've been working on a multi-threaded Ray Tracer for my graphics class, I built a plugin interface for the package that contains the Ray Tracer, and I'm expanding the support for the Collada file format, but besides that all I can think of to say about it is that they're written in Java anything else seems like like it would only interest a specialist or is obvious, I had to do lots of debugging, I learned some new Java functionality, implemented some algorithms, blah blah.

I really like the project and am adding to it because I'm interested, but I don't what to say about it.

So recruiters /interviewers, what are you looking for in "Tell us about an interesting project you've worked on."

People with projects, what would you say about your own projects? Or would you suggest saying when asked the above question.