Well I know that it's interesting enough to buy a 02 uk card and have some credit from fishtext, there are enough countries where it works. Maybe it works for some of the countries as well where it's said there is no 3G but where nothing is written about gprs, when not I can always buy a local prepaid or use one of my international cards. The countries where it where it works according to the site of 02 already saves me enough.

Active sims NL Telfort, KPN, Vodafone, TrendCall, T-Mobile
DE Simyo
CH M-Budget
PE Claro
INT Air Baltic Card, GeoSim
Non-active sims NL Qick, Easymobile, Tele2, Simyo, Rabomobiel, Vectone, UPC, GT Mobile, Orange, Hema, Lycamobile, Carey
TZ Celtel
Malawi Celtel
Zambia Celtel
SA MTN, Vodacom
INT UM, UM+, Go Global Sim, Max Roam, 09 Sim