How to create LOV list of values

I want to select some users from 'n' number of user,
where, right now I'm using textboxes which take search criteria and
populating a list box.

I want to replace the whole thing with an LOV(list of values) feature
wherein I can have just a search button which will popup a window and
take my search criteria in text box and populate the values in same
window so that i can select from them and when i click on submit,
the values selected must be selected for next operation.

How can i achieve that?
Is there any plugin?
Any help is greatly appreciated