Witopia works well. I bought the annual membership. It has a lot of flexibility vs. some of the free ones. Plus you can add the VPN to your smart phone and Skype from it. Some of the free services work and some don't. Witopia works in China also. I've found some of our hotels in China seem to allow internet access and others have areas clamped down. They also know the server ID's for a lot of the free VPN services. Witopia allows you to change to 3 different VPN configs and a ton of servers around the world. The free services tend to use PPTP. Read the statement below:

From the beginning there were two services: Personal, which always included PPTP and now includes ipsec and L2TP and Pro which was twice the price and included OpenVPN. Both are secure but Personal is more easily blocked by governments or corporations as they can usually detect the protocol.