I recently tried out the jQuery Searchable DropDown (v1.0.7) from http://jsearchdropdown.sourceforge.net/ and it worked perfectly except for 2 things:

I'm writing an application that uses NHibernate as the data layer, but is required to integrate with an existing Umbraco system. Specifically, I have a User class that needs to map to an Umbraco member.

Using LINQ and the Enumerable.Range method it's possible to populate a dropdown list of month names in a single line.

A simple javascript function for validating a date that's input using 3 dropdown lists