I use regexp a lot, very useful, but OS X has weak support for them – Apple’s products rarely support regexp for search/replace.
In particular, the latest version of Xcode (Xcode 4) has no support, which is tragic. So … I wrote an app that makes it fast and easy to do a search/replace with full regexp support.
BONUS: it does it all in realtime – so you can see the results as you type (useful if you’re not 100% sure of the syntax you’re using).
It just went live on the App Store, and it’s temporarily at $1 – grab it now, I’ll be putting the price up after the weekend. Here’s a teaser screenshot from the v1.1 that will go up soon: