In this demo I use the PagingBulletedListExtender from the AJAX Control ToolKit. A list of the capital cities in my database is downloaded to the browser (this can be a disadvantage if the size of the data is large) and is then being processed by the client-side script of the extender.

You can click on any item from the index to see a list of cities that start with the selected letter. For example to see information on Victoria, BC, Canada, click on the letter "V" then click on the hyperlink for Victoria to cause the page to partially post-back (using an AJAX UpdatePanel) and retrieve the city, province and country information of the selected city. If you hover over the labels within the information display area on your right-hand side, you will see a tooltip describing the meaning of the value.