I've built a search engine dedicated to searching sites about programming languages (with an emphasis on theory) using the Google co-op services. You can find the search engine at: http://www.cdiggins.com/search/

Now you don't have to append your Google searches with extra superflous terms like "fish language" or "cat language" or "mixin types", you can just type in "fish", "cat" or "mixin".

There is still a fair amount of work to be done to fine-tune it, and increase the number of sites it searches. Let me know though if you can think of ways it can be improved.