I would suggest you go with RadCombo
control (part of RadControls for ASP.NET Ajax that come with Sitefinity). This control supports templates, which means you will not be bound to use text only and has built in auto complete feature.
There are numerous ways in which you can achieve your desired scenario. For more complex data you can use RadGrid
as well, which supports various ways of filtering.
Finally, you can decide to do everything yourself and go with web services and maybe some jQuery plug in.
The first option, however, would be simplest - and I am pretty sure would reasonably well do what you are trying to achieve.
I hope you find this information helpful. Let us know if there is anything else we can do for you.
the Telerik team
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