I use a vodafone wifi and it works very well, sometimes there are three laptops working off it at the same time. Not having to pay for the landline is a great bonus. Sometimes Skype doesn't work very well but I don't know if that is the fault of Skype or the wifi.
I installed a little app on my Nokia E63 (Symbian OS). JoikuSpot (€9 once-off payment to the developer) turns you mobile into a WiFi hot-spot.