There is a great post by the blog at phroogal.com, a website dedicated to giving people practical financial advice. The post (link at the bottom of this page) deals with the topic of credit unions.
I wanted to take the opportunity to chime in on the topic myself. In case you don't already know, a credit union is a financial institution similar to a bank. The difference is that banks are established to make a profit; credit unions are not-for-profit institutions, as established by federal law. So you can go to a credit union to open a savings account, take out a loan, open investments like a 401(k), and so on. Anything you can do at a bank, you can do at a credit union. The only restriction on membership for many credit unions is that you have to live in a certain geographical area.
The benefit of using a credit union is that the loans usually feature a lower interest rate, and the savings/checking accounts sometimes pay higher interest rates as well. Granted, this varies from institution to institution, as well as from one point in time to another. But the general trend holds--since credit unions aren't out to make a buck, they can be a little more generous to their members.
I have an account at a credit union myself, and I'm generally pleased with the service there, as well as the competitive interest rates. I have accounts with banks as well, and they don't pay me quite as much interest (not that an extra 0.05% annual interest is going to make me independently wealthy, but I'll take money wherever I can get it). Since credit unions are also local, you can get to know the employees better and thus get more personal service, for what it's worth.
So, it's definitely worthwhile to check out a credit union near you! After all, the personal service and the extra money in your account can definitely make it worth your while!
As promised, here is the link: http://blog.phroogal.com/everything-needed-know-credit-unions/#.U3_Y_PldUjw