I've heard about the web site Xuropa where you can register then evaluate EDA tools virtually, now Mentor Graphics has a way for you to virtually try out DxDesigner - a suite of PCB tools.
Related articles and forum discussions on cloud-based EDA:
- Schematic Capture and SPICE Simulation in the Cloud
- Article: No Semiconductor Design Cloud Strategy? Really?
- Article: Simulating in the Cloud
- EDA Clearing Clouds or Cloudy Computing?