Unusual Animal Companions

[Fortuna]

What kind of stuff can I have for an animal companion beyond what is listed, if anything? Specifically, can I have a cat?

[Dusk Eclipse]

If you mean a house cat, I don't see why not, mind you, It will probably be really weak

[Rhiannon87]

It's up to your DM. If they say you can have a cat, then you can. As mentioned, it won't be very good for combat, but a small stealthy animal can be useful in lots of other circumstances.

[Foryn Gilnith]

http://www.wizards.com/default.asp?x=dnd/we/20070228a
See Urban Companion for rules for having a cat companion. Not sure how good it is, never tried it.

[Fortuna]

It looks interesting. Could I have Improved Familiar with that?