Definitely gotta reccomend rats.

Like Liesje mentioned, I did breed rats for 6 years, and I also did rescue.
Cita gave you some wonderful info on rats, and I'd like to add some links to the one she gave you:
[link
http://www.ratsahoy.com]www.ratsahoy.com[/link] - My pet rat forum, not huge, but definitely lots of knowledgeable members.
[link
http://www.ratsrule.com]www.ratsrule.com[/link]- There's a link there to [link
http://www.goosemoose.com]www.goosemoose.com[/link], which has a HUGE and active pet rat forum. The members there can be a bit...blunt, but they know what they're talking about. She also has a link to her Suebee's rat diet, which is probably *the* most popular diet among rat owners.
[link
http://www.ratpalace.com]www.ratpalace.com[/link] is formerly, IMO, the greatest rat forum out there. Christy closed down RP last year for personal reasons, but the archives are still there and provide great reading. I actually started Rats Ahoy when RP closed so the members would have a place to move to...so most of the former RP members now frequent my forum.
[link
http://www.ratguide.com]www.ratguide.com[/link] is the BIBLE when it comes to rat health info. It's great to just go there and read and learn about various illnesses and issues- which is important, because good rat vets are few and far between, and its good if YOU know plenty about rat illnesses and the medications and methods used to treat them....because your vet probably wont, and youll need to be able to say "NONONO!!!" when the vet tries to give a shot of Baytril to your 8 week old rat or tells you "rats can't be put under anaesthesia" or something similarly dangerous.
I highly reccomend joing one (or all) of the forums above and learning about everything rat related before deciding to get some. (Obviously, research research research. [

]) Once you get everything down, they're pretty easy to care for. Probably the only area where you'll really have to study is when it comes to nutrition...since there are NO good producers of rat food out there and you *will* have to learn to formulate your own diet. There are a few standard diets out there that can help you though with that, so you're not on your own by any means.
Rats are definitely the friendliest and most social of the small pets. They're very, VERY doglike...and I actually no some people (who don't have predatory pets) who don't even use cages for their, but give them the run of the house. They'll snuggle with you while you watch TV, wrestle with your hand, chase you, play tug of war, ride on your shoulder...they can actually be taught to do most tricks a dog can do, and they can also be litter trained (or barring that, trained not to go outside of their cage.)
They DO have to be kept in same sex pairs or groups, so you would have to get at least two, but two rats are actually *easier* to care for than one...because they'll be much more social and much less defensive towards you if they have a friend, and rats who are kept with friends have less health problems and live longer...saving you vet bills and alot of heartache. [

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I've kept every manner of small pets...and found rats to be the most rewarding. I've been involved with rats for the past 11 years, and don't plan on quitting...ever.[

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As for where to get one...I'm not sure where you're located, but I could probably put you in contact with a reputable breeder who is within a couple of hours of you. If not, you can try rescues...rat overpopulation (loads of irresponsible BYB'S out there [
:@]) is just as big of a problem as dog overpopulation, so there are rescues and shelters that are quite literally overrun. Petfinder is definitely a good place to look.
While I'm no longer an "official" breeder, I am having a litter in the next couple of months....right now I'm planning on breeding one a year or so just to keep my lines going...since I honestly don't know if I'd want to stay into rats if I lost my lines completely. So I guess I *am* still a breeder in a sense- but I no longer will adopt out babies on a regular basis and don't have any real breeding goals. I'm just keeping my lines going for myself, because they're unusually healthy, and because I absolutely love my rats.
But, I mention this because I *have* shipped before....and I will ship rats via the airline of my choice and to adopters who are just so incredibly fantastic that I really want them to have some of my rats. Shipping is expensive, stressful, and time consuming,. so I usually only do it under very special circumstances...so if you did decide you want rats...well, I'll have a litter this summer, and from your posts, you sund like a great pet owner. My rattery website is HORRIBLY out of date, I no longer update it since I'm no longer a breeder...but you can go there ([link
http://www.ratsiclesrattery.bravehost.com]www.ratsiclesrattery.bravehost.com[/link]) to get an idea of what my adoption process is like, and get an idea of what other reputable breeder's processes would be like too. [

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