I'm thinking about starting to play around with water chemistry in my brews. I've been using bottled water with no salt/ion additions without problems, but I want to start tinkering. What would be recommended as a good resource for info on this?

Check Palmer's How To Brew on the web. I personally use Poland Spring (spring) water. It is filtered, but no reverse osmosis or anything like that. So far, i've had good luck. I'd use my tap water, but my city uses Chloramine.

This site will help once you get the basics.

http://nomograph.babbrewers.com/

The How-to-Brew was helpful, and I found that there are some tools in Beersmith for geting to your target concentrations of various elements. Seems to work pretty good.

Get the water test from Ward Labs first. That is the first step and was very informative. They ae quick with their turnaround.

I would get the test strips like the one for the swimming pool water and see how it looks like. If high alkalinity (above 170 or more ), get one which show the hardness too. I would boile the water the day before and have gipsum on hand. I add 1-1.5 tee spoon of gipsum and maybe 2 gal of filter water. It's good to have some minerels for good beer that's why I will mix water.

Have you had your water tested? That would be the first place to start. Then you will know what to add/subtract for each style.