It's Exam Time Again!

This is a map I've been working on for over a year now. If anybody can guess what it's about I'll be suitably impressed and will reward you upon your next visit to London Town. In the meanwhile, it's back to the nasty books. I've got my biggest exams, since the ones I took last May, to prepare for. Four courses, five papers. The first one's on the 22nd of this month, the last on March 1st. Till then!

ANSWER EDIT:
It's a map of all the London pubs, bars and clubs I've been to since June 2007. The green pins are pubs and bars (yes, there's a difference!). The dark blue pins are clubs, the light blue pins are pubs, bars or clubs that I've been to but cannot remember the name of, and the yellow pins are London's famous ancient pubs. On the map above the ancient pubs that you can see are the Cittie of Yorke (founded 1430), Ye Olde Mitre (1546) and Ye Olde Cheshire Cheese (1538). Funnily enough, I've been to over 130 drinking and dancing establishments the past three years, yet hardly any within the City of London itself! Nor has there been enough drunken revelry south of the Thames. So what are you waiting for? Visit soon and we'll correct these wrongs! Right, back to ye olde darned books!

(PS- Click on the map or here to see it in full. The red pins are for restaurant pubs and purple pins for places I've pub quizzed in.)