This very simple Gtk2-Perl program works like an interactive shell built into an editor. You write your code in a multi-line text box, select the code you want to run, then hit keypad-Enter to execute that code. The stdout and stderr of the command are entered into the worksheet for you. This is inspired very much by the classic Macintosh Programmer's Workbench.
If you've ever been frustrated by the single-line entry of the perl debugger or gish and having to retype an entire sub when you change your mind, you may find this interesting.
Warning: this is very much just a proof of concept, a prototype. The editor doesn't do undo or syntax highlighting or hinting or API help or interactive debugging or file loading/saving or really anything other than just let you highlight and execute code. Contributions welcome. :-)