T-Mobile has a great offer in the Netherlands: unlimited GPRS and WiFi access on a smartphone for only € 9.95 a month (that's about $ 8.65). I just signed up because I have a qualifying smartphone (Qtek 2020i) and T-Mobile subscription and I think it's a really compelling offer. Admittedly the number of WiFi hotspots is still quite limited and GPRS is not very fast, but still good value for money.
Last month I had to call 0900-9292 to get information about the departure time for a bus. Just that call cost me a long wait and € 6.50. Now I can get the same information faster and cheaper if only http://www.9292ov.nl/ would be more PDA friendly ;(