I bought one of these "MiFi" devices a while back and it's a great little device. It's getting a bit old now and there are newer models, but I'm sure there are still a lot of them floating about.
I originally purchased mine on eBay as an unlocked model, but they can easily be unlocked for any network using the software over at DC-unlocker.
The default firmware that came on mind was branded for three.co.uk and is fairly limited in what it can do. By flashing the device with a stock updated firmware from Huawei, it was possible to unlock additional features, such as web-based management (no more using Windows to configure!), automatic WiFi-on, and the ability to use the WiFi even when the device is connected via USB.
Warning: updating firmware could possibly brick your device if performed incorrectly. If you're not confident doing this, please don't!
You can find a tutorial on how to download & install the firmware here.
Good luck!