I just switched to mobile broadband because it's cheaper than having to pay line-rental and fixed-line broadband. You can get some really good deals out there as long as you don't mind losing a little bit of speed. Unfortunately, despite coming with a nice white USB stick the 3 mobile package is a mess on Mac.
Using the connection software on the Huawei E160G HSDPA stick, you can connect to the internet but I found that it would crash within about 1/2 an hour every time, bringing the whole system down. It's the only thing I've ever used which crashes my Mac so that's a poor result. I did some googling and found one suggestion that the driver sends too many messages to the system log but changing this made no difference. In the end, the solution seems to be to use the built-in connection software instead of 3-Connect i.e. use the little phone icon in the status bar. Using that, I haven't had another crash yet... woohoo!