I started to evaluate MyClanPlan as I have an actual use for this, but I stopped when I had to provide an email address. I don't want to provide an email address, and I don't think I should have to. I think many other people will stop at that point too.
Here's a suggestion. Ask someone for a "password" and generate your "random" link based on that. Put it on the page, and don't email it to them. Allow them to use the system without an email, but offer some features only with an email. Offer reminders, or invitations, or something like that, but only with an email. In this way people can use and evaluate your system without exposing their email, but gain access to more features when they know it will be useful.
Limit the number of reminders, etc, on a free plan, and then offer unlimited reminders for a small fee. Then put ads on the free versions, and remove them from the paid for version.
Just thinking through the keyboard - feel free to ignore me. I like the idea, I'm just not willing to give away my email address that easily.