I've been reading with interest, for a while now, that http://weblogs.asp.net/infinitiesloop/ has a rather nice textbox auto-complete extender. Lots of people have had lots to say on the matter, so I'll be short: I've had trouble getting the code provided to build and run, even with the assistance of the links provided on the blog entries.
The most useful entries (to date) appear to be:
Having downloaded the files I played around and got it all nicely working. I really have to hand it to I.L. because having state information available where the http://ajax.asp.net/ajaxtoolkit/ forces you to use a webservice (and thus lose all context of the user's session, etc) if invaluable.
My personal use for the context is to specify a locale for the searching of brands where users in different locales would get different results. I think the most obvious would be the searching of a user's personal history of textual terms.
Anyway, I've got the solution and all the .dll files required, in a .rar here: