Hutch MBI service allows you to connect to the internet wirelessly from almost anywhere in Thailand. Once you own the modem, you pay 1000 baht/month for unlimited use.
Used only for one month. I changed condos and was able to get DSL so I don't need the modem after all.
This model is in short supply, being the cheapest one, and the only one compatible with Mac OS X. I had to go to Bangkok to get one (out of stock in Hua Hin).
All original stuff included*: modem, software CD, headset, box. Modem is like new, not a scratch.
Price: 3500 baht (New: 4500 baht)
* I'll include the SIM card if that makes sense to do. Getting the service disconnected tomorrow, I'll ask if the SIM card came with the modem purchase or with the monthly subscription.