Is there a free way to do quality a/b testing in an efficient and helpful manner?
Are there any sites that are known to be the best and most helpful in this?
Entirely free is Google Website Optimizer which is pretty quick to get going with, but also pretty comprehensive. There's a couple of books available from Amazon if you should need them, and quite a few sites out there giving hints on it. As far as I know it's the only free one, but does full multi goal multi-variate testing, albeit not with realtime results.
There's a website which lists all the known multi-variate tools and compares them here: http://www.whichmvt.com/
You can get 30 day free trials from both Optimizely and VisualWebsiteOptimizer I've been using VWO and am very pleased. Both look like they should do what you need. I'm not aware of any sites that offer A/B testing of that quality for no cost- we'll see what others say.
Check out http://visualwebsiteoptimizer.com/ I am using it since last week. The set up is very easy and intuitive and support is awesome, at times you may get answer within 2-3 mins of sending an email.
Unlike GA it provides real time reporting which is a boon when you are in midst of huge incoming traffic.