When I was a teenager my best friend and I each had a gerbil for pets. I never did get very attached to my gerbil, as he was rather aggressive...and so I assumed that all gerbils were that way, and never had another one after that. Apparently though, that they do make very good pets when handled properly.
btw, did you know that as a defense mechanism, the gerbil can detach its tail? Well, not the entire tail exactly...but the fur and skin will come off. We found that out the gross way when my friend's gerbil was trying to get away from her, and she managed to grasp his tail before he scurried under the sofa. Unfortunately, he clung to the carpet and pulled...and suddenly he darted away, leaving my shocked friend holding nothing but a *tail casing*. I can imagine the gerbil wasn't very impressed either....his tail was never really the same again. :?
Oh, and rule of thumb: don't mix gerbils and rabbits....another mishap that occured whilst I was a gerbil owner (don't forget, I was still a pretty wet-behind-the-ears teen) happened when I decided to take one of my bunnies out in the yard one day. I also thought my gerbil would enjoy the outing, so I carried them both out in a box...the box had a divider down the middle, but not top on it. Well, when I set the box on the ground the gerbil leapt up, grabbed the bunny by the cheek, and wouldn't let go. I tried to get him to release his grip, but he was stubborn...so I had to wait until he decided to drop off by himself. The bunny, for whatever reason, didn't seem too put out by it; at least he didn't have a wound that I could see. Still, it was a strange sight, seeing a rabbit with a gerbil hanging off of his face.