CONSIDERATIONS:

- http://limitedlist.com/list
The listing of lists doesn't scale horizontally so the browser needs at least 800px width. This will break a lot of browsers (think mobile). It's obvious the designer like the look of the three-across the page, since it does scale in higher resolutions while maintaining three-across (i.e. three-across is forced). The problem is when you force this, your design breaks on some browsers/devices.

- Add List Item
The initial 'add-list-item' is just an unlabeled textbox, so the first thing I entered was an URL. Needless to say I did it wrong. The first textbox is the 'title' of the item. When trying to correct my mistake via 'edit' I was faced with three unlabeled textboxes. The first (single line) textbox had the URL I had entered. The second (single line) textbox was empty. The third text box was multi-line (I believe this is for comments). The various entry fields SHOULD be labeled. --You're free to expect me to read your mind, but don't be too surprised when I fail. ;-)

- The home/landing page is very sparse. It's easy to see you were aiming for a 'clean' home page (good), but the problem is most people will have no clue what the site does (bad).

- popup when adding an item to an existing list
When adding an item to an existing list, the tooltip-like popup letting the user know "thankyou and moderators will look at the submission" disappears too quickly. You should make the user 'close' or 'confirm' the popup to be sure it has been read.

- http://limitedlist.com/about
The 'about' page does not clearly state what the site is about, how the should be used, or most importantly, why I should want to use it.

- security/permissions
If I create a list, am I the 'moderator' of that list? Can I allow/disallow other users to add items?

- update notifications
If I create a list (or subscribe to a list), can I get an email/sms/IM/twiter/FB/whatever message sent to me every time a new item is added to it (or other change updates)?

- spreadsheet
Other than a pretty interface, what advantage does your app have over a google spreadsheet?

(Yes, I often ask the pointed question above and I probably seem like an ass for it, but it really is an important question to ponder very deeply.)

- Integration / API
If I created/moderated a list and wanted to integrate it into my own page, there's no way to do it. I might want to integrate the list onto a page on my own website, but more seriously, I can see where integrating a managed list on a FB 'home page' or 'fan page' or similar could really be desirable. I'm not a FB user, but even I can see how such integration might make your site/app really take off, and similar could be said for other social 'user-home' services (gmail, yahoo, myspace, youtube, ...).

- Useful?
Though having and Internet based, multi-user list is an interesting concept, I cannot think of what I would use it for? (NOTE: this could be entirely my own fault due to lack of imagination and/or coffee)

COMPLIMENTS:

- The design is nice and clean.

- I like your use of drop-shadow.

- I was VERY pleased to see the 'thumbs-up' icon was not a FB 'like' button.

NOTES:
- If you had hierarchy of lists, you'd essentially be recreating a web directory (see dmoz).

Congratulations on shipping!