I just tripped over a free AWR transmission line calculator available on their site for downloading. It also has a smart phone application, also free. Polar9000 is a great(but not free) tool.
If you want more details Wadell's Transmission Line Design Handbook is a good reference.
Azulykit
You might like this too: h**p://w*w*w.microwaves101.com/encyclopedia/microstrip.cfm