Dynamic Select with Text Entry

[sjm133]

I know I've seen a script around, somewhere at least, that is sort of a combination text box and html select.
What I need is a single page item displayed as an HTML select. The select would have prefilled items in it just like a normal select. However, if the user wants an item that is not in the list they would be able to type it in.
I know it sounds weird but this will be used as part of a search page to allow users to enter, or select, a number of search results per page. The list would contain values: 5, 10, 15 20, etc. but I've been asked to also allow the user to enter the number they want. I'm tight on real estate so would like this in a single element. Like I said, I know I've seen a script like this somewhere but can't seem to find it now. Anyone have any information on such a beast?
Thanks in advance.

[Nile]

There is no regular tag for doing this in HTML. But I'm sure you can find something online like this, I'm looking right now.