Is there a way to make the value of a column when creating a new list
item be assigned based on a URL parameter?

What I'd like is to assign a value for say, the "Company Unit" column
based on from where the user clicked on "New Item". Like if there's a
view of the list based on the where the "Company Unit" is "Human
Resources", I'd like to be able to set it so that when the user clicks
on "New Item" in that view, the new item form already has "Company
Unit" set to "Human Resources." Same kind of thing when "New Item" is
clicked on other views of the same list.

Is this possible in SharePoint 2003 or 2007 without programming a new
web part? If not, does anyone know where to get a webpart?