For the past year or so, I've been paying for and using a VPN service called VPN Unlimited. I use it on my Macbook Air and my iPhone. I've never experienced any downtime with it, and it seems to be fast. The company claims not to keep logs of websites their customers visit.
Our partners at Stack Commerce are offering a lifetime subscription to the VPN Unlimited through the Boing Boing shop for $39. Should you get it? I don't know. Quite a few readers have been critical of the service. Here's one BBS thread, and here's another.
I would love to hear recommendations for other VPN services, and will switch over if I learn about a better service as long as the price seems reasonable.