Any router will do if you're willing to drop the firewall . But remember both (or all) parties will need to either have a no-firewall solution or be willing to 'mess about' with ports.
You don't say where you are from. Netgear's DG834GT seems to get a lot of good reviews and should not pose problems for iChat. It costs 65 Sterling / 95 Euro. However, it is not available in the US or Canada.
I have that Netgear router, and it's anything but no-fuss. The firewall is (rightly so) on by default, and therefore, you need to open the bazillion ports that iChat AV wants.