Been trying some traversal strategies, treating the dots as directions (with blue as the start), and then collecting whatever letters I pass over. Most of them hit endless loops quickly, and all the ones I tried eventually do. This one went further than most before hitting a loop:

blue: right
red: left
green: down
yellow: up

Starting with the blue and using those rules, I get a path like this: http://imgur.com/8SKHIQU which crosses these characters: 3F9aAi

That doesn't seem to contain any useful information and doesn't work as a string on the sites that do take strings that short... not sure if this sort of thing is the right direction or yet another rathole.