This is not just a poorman's Matlab(C), but a hell-serious math package ! It is really mature and horribly fast. I wrote a 3d continous CA within hours. The learning curve is significant, but its power is overwhelming. The mailing list is extremly responsive and the developers are great. Surely its intensive use in serious astronomic/academia projects boosted its versatility and design.
Gtk2 is really a perl yedi's lazer sword. I was so amazed by its speed/elegance and versatility. The documentation and development is done by a dedicated group of hackers. Gtk2 has become surely *the* major gui toolkit, soon superceeding Tk by far.
I plan to use it in some serious academia projects. In the past i often heard complains about Tk (and was always ashamed of its uglyness/slowness/win32-gui-alienness). It was hard to sell it to my boss's and collegues.
Pitty: I got only a not-very-recent version installed with the aid of homepage.ntlworld.com/wayne.keenan/gtk/ on my activatestate win32 machine. It also did not install via CPAN shell on my recent cygwin enviroment (failed some to install some auto-dependencies).
With Gtk2 i feel like getting serious with perl and guis (on win32 and linux).
I was in need to hide IE decoration and direct it to a form from cmdline. This module did the job so well, even though it is capable of more. I am sure it will also help so many IE users to write semi-automated scripts (with human intervention via IE).
Eventhough Damian has iconic status i *objectively* rate this module as excellent. I am convinced that this module fuels rapid p6 adoption by p5 people. And of course, thanks to all the sponsers of TPF and therfore this fantastic module.
Nested conditional expressions is this modules' plus (IMHO attest/artifact of authors dba experience). It also supports various significant SQL dialects. -1 for the package contra object syntax/api in the documentation. Overall also a very very excellent module in its category and may be the best (in terms of simplicity). I am looking forward to use it a lot.