I'm in Seattle right now sitting in a conference center on Wifi using OpenVPN. OpenVPN allows me to remotely connect to my work network and access all my "internal" resources (mail servers, admin boxes, etc) as if I were back in Oregon sitting at my work desk. On top of the connectivity it's highly encrypted and thus secure even in a non-secure environment, like conference centers with free Wifi.

OpenVPN is extremely simple to setup with only two configuration files, one for the server and one for the client. If you're looking for a simple and cheap (free) VPN solution I highly recommend OpenVPN. With OpenVPN clients for Windows, Mac, and Linux it's usuable just about everywhere you'd need it.