increasing speaker volume?

Besides pressing the volume up button at the top of the keyboard? Nope.

Buy some Bose speakers for it. Now you've got sound!

itunes and vlc have software amplifiers (vlc on the player, itunes in the eq), those can give you a boost but you might loose quality.

http://www.bongioviacoustics.com/products-dpsplugin.php

i also highly recommend Twelve South's BassJump

Another option is AudioHijack Pro.

I use it on my MBP 13" to set higher audio levels for Safari and Quicktime, it does a great job.