I hope this is kosher...I'm actually posting a solution. I searched and searched and didn't find the answer in the forums, but finally figured it out myself and figured I'd share it.
I was wanting to make a "Home" tab in my main site menu that took the viewer back to the home page. They could click the site name to get back to home, but I wasn't sure that everyone would think to do that. I found a lot of solutions involving changing my php code, etc., but ultimately found there's a super-easy way to do it in the dashboard that I had simply overlooked.
Under "Appearance" chose "Menu". The second box down on the top left says "Custom Links." Just put your url in there, put the name you want to appear in the menu into the section that says Label, and then say "Add to Menu." Then, go to the box in the right that says, "Save Menu." Ta-da!
I don't know if this is a new function of the latest WordPress or whatever, but I was very excited to find such an easy solution. Sorry if it's obvious to everyone else. My theme is twenty-eleven. The site is http://www.aitcn.org if you want to see it in action.