the team had an LXR setup to do project wide searching, however it was aging and having problems, and is a bit difficult to work with.
As a side project intended for a report once I was back on campus, I set up OpenGrok, which worked brilliantly, and was reasonably easy to configure, and nicer to use once we got it setup. The team liked it enough that they switched to that permanently.
both are open source, and were built to handle large code bases (LXR was built for the linux kernel, OpenGrok for when Sun open sourced Solaris).
Another one I had tried, which was very easy to setup was Gonzui. It's also open source, but didn't really handle the huge codebase as well as OpenGrok or LXR. For under 100k lines, it's probably fine, and the ease of setup may be worth it.
All three provide a web interface, and do indexing as a separate process from search, so we would re-index the code base nightly. works very well for larger teams, might be overkill for what you need though.