How do I use text input to search a taxonomy, in a custom search form?

I would like a custom search form with search "input form" to query a certain vocbulary.

I have looked at views, fastsearch, filter block

They are ok to use when you want a drop down, not a "text input". I have about 450 terms, from a vocabulary I want to be queried.

I believe a drop down would not be user friendly, also it would load as fast.

On my site, a directyory listing, the search form would be of this nature

|keyword| |location| |business type| Search Button

where "keyword" is a text input of the user's choice, "location" is a vocabulary associated to directory entries "business type" is also a vocabulary associated to directory entries.

A few example of such search forms would be:

http://www.yell.com
http://www.touchlocal.com/

Thank you