Other useful resources for RF Design
1) The Designer's Guide Community: www.designers-guide.org
This is a good resource for simulation and modelling of analog, mixed-signal and RF circuits. There are also several papers on different aspects of design, simulation and modelling.
2) AppCAD: www.hp.woodshot.com
This is a very useful windows-based program (originally from HP, and later Agilent) that can help perform engineering calculations for a variety of RF/microwave applications.