Here are some notes about the app that I found interesting while making it. Most important is that this is Firefox 2.0 and WebKit prefered. Safari does work but the JS is slow on it. WebKit screams with client side JS implementation speed.
1) I coded my own extension to Acts As List ActiveRecord modules and custom client JS functions that use the Sortable objects on the page to self serialize new information and logic past the normal Array of Sortable.serialize. These custom serialize params minimize sortable SQL queries to only the object that gained the dropped element and where it was inserted. Limiting SQL queries to about 3 or 4 for any sortable action.
2) I really also like my own modal code that I came up with (alot like Lightbox) that is also used for the page modal on the Bookmarklet.
3) I am using a lot of fragment caching and wrote some interesting helper modules (for a newbie) that the whole application shares for expiring fragments appropriately.
4) The app is hosted using Apache2.2/Mongrel
5) Take a look at the action area and its Inbox and Trashbox. This is a largely overlooked feature when using the demo for the first time. I use the tilde ( `/~) hot key to open it up.