Dawn dishwashing detergent for cleaning, rinse with fresh water and dry, then apply Pro-Link Gold. Best to let the ProLink set overnight, but it works well even if you get right back on and ride. Wipe down every now and then with a rag wetted with ProLink.

I tried Purple Extreme for a couple of whiles, but found it didn't work as well as ProLink, and the chain started squeaking before the advertised 400 mile interval.

Tri-Flow is a good wet lube, but it tends to get kind of messy, and just about as much tends to get on my sock or ankle as stays on the chain ;-)