Airvpn is worth a look.
They are very open about their server load so you can judge which one to connect to.
They have some guides on the site for Tomato and DDWRT and you can download custom Openvpn config files.
I even managed to get it working with a Synology NAS. The problem being having to use a personal certificate as opposed to just a username and password.
This is a speedtest through one of their UK servers: