Post Rain Ride Wipedown I've tried avoiding riding during the rain for years because I didn't want to hurt my bike.  But, tomorrow I really want to ride, rain (most likely) or shine.  What should I do after the ride to ensure my bike remains in good shape?
Your title answers your question. 

After the ride, wipe down the bike so that there is no excess moisture. Make sure that the bike is stored indoors, in a dry, warm environment,  so that any remaining moisture can evaporate.

If you have a steel frame, consider using a frame preparation like Frame Saver, if you're going to ride in the rain regularly. 

And last, make sure you do you regular maintenance. Open up all the bearing areas (hubs, headset, and bottom bracket) and clean and grease them regularly. Grease is protection from water and corrosion as much as it is a lubricant, so this is important to keep it running smoothly, as well as protect from weather.

I hope that helps.