Here's an even easier way to improve iGraph coverage! Just cut-and-paste URLs into the following form and I'll take care of the rest. (My previous multi-step howto only resulted in about a half-dozen submissions..)
You can find a list of uncovered sites here:
http://s/?fileprint=//depot/google3/googledata/quality/igraph/userid_handler_defs/README
By doing this you'll help improve the social search, improve authorship detection and make building the implicit graph easier.
https://spreadsheets3.google.com/spreadsheet/viewform?formkey=dGg0aFpOLW9JVWpCa0t3d2ItR1BlSVE6MQ
#googplus