Google Code Search has indexed Subversion and Mercurial repositories, so people can search open source projects. How can I do the same for my company's repository with the least effort and without publishing our code?
We have Trac (with Subversion) at our shop, but it only indexes Changesets, and we also have Visual Source Safe.
A quick Google turned up VoilaSVN but I cannot vouch for it.
Edit: It also turned up OpenGrok which appears to have a lot more support for other systems.
Commercially, there's Krugle Enterprise. If you want to see how it works, you can use http://www.krugle.org/ to search open source projects.
there's always lxr (linux cross reference). Mozilla uses
It'd take a lot of effort, I think, because it's only available via git repo. More power to you if you make it work. git://lxr.linux.no/git/lxrng.git
I can vouch for the usefulness of opengrok, we have it at work and I use it pretty well every day.
Surprisingly, I've found that the built-in search capability of Vista are very helpful. I've just added my source tree to the indexed directories, and get quite fast indexed search.
It is not language-sensitive, however.
Our langauge-sensitive source code search engine can be found at SD Source Code Search Engine. It can handle many languages at the same time. Searches can be performed for patterns in a specific langauge, or patterns across languages (such as "find identifiers involving TAX"). By being sensitive to langauge tokens, the number of false positives is reduced, saving time for the user. It understands C, C++, C#, COBOL, Java, ECMAScript, Java, XML, Verilog, VHDL, and a number of other languages.