You know what would be a great Salesforce.com feature? If you could test and evaluate different licenses. Sure, you can get a free 30-day trial if you're not a customer. But what happens if you want to evaluate a "Chatter Plus" seat, or an "Unlimited Edition Seat"? How can you tell if the seat will meet your requirements and work within your existing environment?
Me, I want to be able to implement a test -- to see what seat would look like -- before I commit to changing my contract. Is it too much to ask?