I quite often use ptkdb among other things, which visually looks quite well like an IDE, because of its step-by-step debugging, and ability to watch for variables.
Its not an IDE, but must-have anyways.

addition: of some relation to your question, the VTCL IDE is usable from Perl for GUI design, although I, personally, rarely use this approach, and this is not perl IDE (but still a powerfull addition to the one's toolbox).