relationship handling and scaling


I am curious how others are handling selecting valid values
from large lists.

By way of example, I have a user table that tracks the
mailing address of the user. To gather the state code, I build a dropdown
that has all of the possible options, and it works fine. No response time
issues or anything. I suppose this type of dropdown list could probably
scale to perhaps as many as two or three hundred entries before it starts
getting unwieldy, both for the response time, as well as having the users deal
with such a large list.

In another case, the user needs to select one of some 15000
valid entries. The user does not want to scroll through them all, but
needs to have some way to search over them and select one. In my old mainframe
days, the user could either directly type in the record key if they knew it, or
hit a function key to pop up a list, and then populate the screen field with
the selected record key from the popup.

What is the rails way of handling large select lists?
Ideally, it should work regardless of whether javascript is turned on.

Along the same line, I have a one-to-many relationship
between two tables. When editing the master record, I suppose the bottom
part of the form could show a set of rows containing the children. I’d
like to in-place edit the children rows. Is there a public example of how
to handle the view and controller actions in such a case? Or are there
better practices for dealing with the user interface aspects of a 1:m

Thank you for any advice you can offer.