Here's another that I'm quite excited to try. I've seen recipes for just about everything homemade, but not dishwasher soap. However, Louise's Country Closet recently posted one! The recipe is so simple too, with only 4 ingredients: borax (1 cup), washing soda (1 cup), epsom salt (1/4 cup) and lemon juice. Mix it together well and let it set up in an ice cube tray. I'd suggest mixing the powders first, so that they get evenly mixed well and each load will clean the same. The ingredients will disinfect it well, too.
For a DIY rinse agent, I'd suggest using white vinegar. I started using it because the bottles are so expensive, and I like how my dishes turn out so much better. Plus, when it's washed you don't have any chemical residue (as I'm sure have to be there after a chemical rinse agent is used). It works great even if you have hard water.