Best Answer - Chosen by the Asker
Go to this website: http://rifmovnik.ru
(1) Enter any word in the blank field, i.e. noun, adjective, verb, etc.
(2) From the dropdown menu that says "рифмы" choose "словоформы"
(3) Click "найти"
When you look for a verb, notice that they also give you a link to the corresponding perfective/imperfective form(s).
Hope this helps
