A friend/colleague and I have just set up a Site to Site VPN using a pair of Netgear DG834G routers. Surprisingly easy to accomplish (as long as you have the very latest firmware) - strongly recommended.
As soon as we twigged that one of the ADSL lines was a dynamic IP, and set up the other end accordingly - it all clicked into place.
Of course, it took longer to dismember his mangled DG834GT (from Sky Broadband) and dig out the necessary settings to log in via the G.. but hey. You can't have everything!