The Artistic Artnet products work well - the rack version is a bit over-spec'd but the up-lynx box is good value.

Check out their website and look out for new products at Plasa...

If you want a smaller widget - the SandBox EMX2/10 offers 2 bi-directional DMX ports and easy Ethernet connectivity - but do check that it works withot the software running on a PC somewhere on the network.... mine doesn't for some reason - and it should!......