Internet
Free wifi access is plentiful at local cafes. Additionally, a county government project (http://wireless.ewashtena...) is underway to bring free or low-cost Wi-Fi to all of Washtenaw County, starting with downtown Ann Arbor. As of April 2010, the Wireless Washtenaw network is visible but not consistently usable, so seeking out a cafe is a better bet.
Digital Ops
Internet access and multiplayer gaming facility with mostly PC video games. The atmosphere is very friendly and social.
Espresso Royale Caffe
This particular ERC location, across the street from the University of Michigan Diag, has a handful of desktop computers set up for customer use. Most cafes in town, including the other ERC locations, provide only wifi, not computers.
Ann Arbor District Library
The main branch of the public library, located downtown a couple of blocks from Main Street (http://www.aadl.org/about...), offers wifi and a couple dozen desktop computers for visitor use. Check in at the desk on the second floor.
Ann Arbor is generally a very safe town, though the usual rules about common sense being aware of your surroundings after dark and knowing where you are going apply here as they would anywhere. The only really common crimes in town are those that you find in any other university town. Theft is the biggie, as many university students who leave their bags unattended in the library or those who fail to lock their bikes can tell you. There's also the occasional mugging or sexual assault, but these tend to occur after dark, so if you're not wandering the streets at 2AM, you probably don't have anything to worry about. Having said that, wandering the streets at 2AM in downtown Ann Arbor is generally quite safe and not at all frightening; there are usually enough students out partying or hanging out with friends until the wee hours that you won't feel like a lone target, or like you're in a dangerous crowd. U of M Police, Ann Arbor Police, and the Washtenaw County Sheriff patrol regularly and are not difficult to find--indeed, alcohol violations such as drinking on the street from an open container are vigorously policed. There are emergency phones located all over campus.
radio stations
Four good public radio stations are within listening distance.