I feel like a section on the Theorytab page where users can request songs would not only be helpful, but would attract many more to the site. As of now i feel like there is a communication divide between those who can create the theory tabs and those who cannot. A long with this, if users could vote on songs that are requested, so that if you look at the weekly list of song requests and there are X amount of people that all want to see someone create a tab for one particular song, it would make this site even more interactive between those who visit the site and do not create tabs and those who are frequent tab creators.
Another way I imagine this site gaining users and daily visitors would be through a point system like reddit. If you create a tab that is recommended you get X amount of points and then people can vote on your tab. Comments could be voted on as well. It would add more incentive for creation, discussion, and general communication.