I had a pet jumper in my first apartment. He would follow me and my wife from room to room, wave at us, and sit by the sink when he was thirsty. We gave him water and called him Steve.
There's a reasonable pet trade for them. I never had the heart to put one in a box though.
The most interesting interaction I had was watching one hunt a fly. The fly landed, and it crawled down on the side of the board the fly was on, out of sight. It emerged behind the fly, then snuck up on it, similar to how a cat does (move, pause, move, pause). Then, when it attacked, it didn't jump at the fly, but jumped up in the air where the fly would be. It grabbed onto the flys back, then rotated, so the spider landed on its back, so the flys legs would be straight up, so it couldn't try to crawl away. It bit its neck area, waited a bit, then dragged it away. Really amazing, especially considering the fly was about the same size as the spider's body.
I had a similar experience with one many years ago, but with the differences that it happened on a chair, and another fly tried to save his "buddy", which I had never seen before. It was like watchin' somethin' from the Nature channel unfold right there in "real life" in front of me. Smartest little spiders I know of. Amazing little critters for sure.
They are small like another poster mentioned, but their big primary eyes and their behavior makes them seem a lot less threatening than other spiders as well. For example, if they notice you they tend to reposition themselves to get a better look at what you are. They are also pretty rare to find indoors, which means you're not likely to be surprised by them while brushing your teeth or taking a shower.
