Usually, 'tips & tricks' articles are a mishmash of good and bad. This one is pure gold.
This jQuery plugin supplies an easy way to unobtrusively add a letter-based navigation widget to any UL or OL list. An easily stylable (via CSS) nav bar appears above the list, showing the user the letters A-through-Z. Clicking one of the letters filters the list to show only the items in the list that start with that letter. Hovering over a letter (optionally) shows a count above the letter, indicating how many items will be displayed if that letter is clicked. Other options give you control over the basic functionality.
A realy nice analogy describing the MVC pattern