Normally in a good KDE desktop distribution ( this obviously doesn't include Red Hat Enterprise Linux WS release 3 w) a developer doesn't need to look for tools. Everything a developer needs exists. Starting right from an Integrated Development Environment with support for CVS/Subversion integration. If one is not is using KDE as a primary desktop one invariably needs either emacs ( if you have listened to "old" hackers ) or Eclipse (loaded with plugins).
For budding perl hackers the recommended plugin for eclipse can be installed directly using Eclipse->Help->Software Updates->Find and Install
from the update URL http://e-p-i-c.sf.net/updates.
This plugin includes a built in Regular Expression editor. This can be accessed at Window->Show View->Other->EPIC->RegExp.
Another very good plugin is
QuickRex. QuickRex supports Java style regexps apart from regular Perl and awk regular expressions. It also allows saving test text for regular expressions as well as the regular expressions