Metamill (ex. trial, $125, Academic $10 (min. 10 reqd))
http://www.metamill.com/

ObjectInsight 2.1 (ex. trial, $499)
http://www.object-insight.com/

MagicDraw UML (ex. demo, Personal Academic Edition Standalone $49)
http://www.magicdraw.com/

Objecteering UML
http://www.objecteering.com/products.php (price N/A, at request)
  Personal Edition: http://www.objecteering.com/packaging_personal_edition.php

objectiF
http://www.microtool.de/objectiF/en/

Software through Pictures
http://www.aonix.com/stp_uml.html

Artisan
http://www.artisansw.com/products/products.asp

Embarcadero Describe (pricing on demand)
http://www.advancedsw.com/products/describe/dedatasheet.asp

Ideogramic UML
http://www.ideogramic.com/products/uml/

iUML
http://www.kc.com/products/iuml/index.html

Visual UML
http://www.visualobjectmodelers.com/products.htm