KoL Familiar Tool
Kingdom of Loathing Familiar Tool by Xylpher (#540421), originally at http://www.few.vu.nl/~rminne/kol/kolfamiliars.php.
Choose your own familiar from the list, make sure the other boxes match what you see in the Arena.
Thanks to http://www.the-rye.dreamhosters.com/familiars/ for the already excellent familiar tool available there, which I used to get my info from.
I can not be held responsible for any loss or personal injury incurred by use of this tool.
For all the people who are nagging me for the source: Fine. Here it is. I suppose it's okay if you wish to put it up on your site or use the source to put into your own tool, just don't forget to credit me.
Note that this tool will not yield 100% perfect results. I thought every battle would have a weight at which you would get 5 XP when I started building this, but it seems they don't. So there might be occurences of losing or getting 4 or even 3 XP. They should be sporadic though.
Modified by Phlip (#509981) to pull the information on the current house familiars from Noblesse Oblige's Kingdom Calendar of awesomeness.