At least, I can't see any free plans, only a 30-day trial.
I'm also intrigued by the difference in subscriber rates between freemium webapps and freemium webgames.
http://lsvp.wordpress.com/2008/06/09/successful-mmogs-can-se...
The numbers from there vary from about 5% to 15%.
What can freemium webapps learn from freemium games?
Games have some advantages that can be hard for apps to replicate; games are, in general, more social than typical applications. Games are also somewhat more enviable. When I was 11, a few friends and I played RuneScape (remember runescape?). After one of us got a paid membership, everyone else suddenly got way more interested in having a paid RuneScape membership. That is to say, if one person gets a paid membership to a multiplayer online game, other people in their social circle will probably be more likely to subscribe as well.
Taking advantage of this with a webapp would require that you provide something that someone either finds worthwhile showing off or something conspicuous enough that they don't have to. The second condition applied for Apple's iPod in the early part of the decade. It'd also probably be a good idea to offer benefits to groups of paid members as well as to individual paid members.
If you make an enjoyable product, typically you can convert interested casual users into paying customers fairly easily.
People want to save time so that they can spend more of it -having fun-. If your app doesn't create happiness directly, save them as much time as you can so they can get that happiness somewhere else. People will pay for this.
We also offer a 30-day free plan: 1 server, 3 plugins, and a 30 minute reporting interval.When you sign up for the priced plans the sign up form asks for credit card info and promises 30 days free. The "Free" link goes to this sign up form: https://scoutapp.com/accounts/new?subscription_id=2 which doesn't ask for any contact details, and clearly shows the price as $0.00.
Besides, I don't think the guys running Scout would refer to their service as freemium on their blog if they didn't have a free version. Their help link at the bottom of the website is also broken ( http://scoutapp.com/info/help ), which means the the website probably hasn't been tested/proofread very carefully (understandably -- there's so much to do).