The title is fun, I know (and I love Lords Of The Rings).
Mapstraction has kind of a similar logic. It provides a common API for the major mapping providers. This means, when you code with Mapstraction API, you can easily switch from Yahoo Maps to Google maps or else.
You can even use this power to create creative solutions like this syncronizing maps example:
Similar to Ext Grid, but built on jQuery, Flexigrid is a feature rich data grid with resizable columns and a scrolling data to match the headers, plus an ability to connect to an xml based data source using AJAX to load the content.
Features of this jQuery data grid plugin:
Sortable column headers
Can convert an ordinary table
Ability to connect to an ajax data source (XML only)
Requirements: jQuery Compatibility: All Major Browsers
Some MooCrop features:
Completely customizable CSS styling
Detects and handles multiple CSS box models
Allows for masking to be toggled
Ability to hide resize handles during drag
Custom events for your own modification
Relative based postioning rather then absolute (should handle overflow properly)
Works and retains layouts on floating images.
Resize from 8 different directions
Ability to set minimium size limit
Cleans up nicely, leaving your DOM in its original state when removed.