I live in Montreal, but being somewhat older than I am guessing you are, I drink my beer at home on the weekends so I can pour myself into bed relatively early.
I found these links:
Best of Montreal 2006 (http://www.montrealmirror.com/2006/051106/bom06_5.html - broken link)
Montreal Nightlife
Go Montreal
Montreal Plus
For amazing steamed hot dogs and poutine, you must visit the
Montreal Pool Room.
I haven't been to most of these places, but I'm sure you'll get some ideas by glancing at these sites. You can google "Montreal night life" and look at some of the sites that pop up.
Buy a copy of the Montreal Gazette (or look at it online) to check out what's going on while you are here.
I'm sure you won't feel lonely while you are here...Montrealers love to party and I guarantee that you'll have a good time.
Cheers!