Me too. I went DEEP into mod_rewrite, mod_proxy and friends in the early 2000's. It's a dangerous place to put too much logic, but also incredibly powerful. On multiple occasions, I used it to solve problems in a couple hours that would've taken the engineering team weeks or months to address.

Yep, and I had a whole bunch ready to show off! I've even given talks about them at conferences! B^>

I'm curious if there is a useful connection between Apache's rule and other term rewriting. Some sort of static analysis? If there is a interesting database of them, I'd add it.