Citation analysis and burst algorithms are being used to create maps of scientific knowledge. Katy Borner of Indiana University, USA seems to be doing a lot of the work.

"Ultimately, I'd like to see a map of science in schools, as common as the political world map," Borner says.

Data on ageing research form a mountain range of information
"'Continents' would represent the diverse areas of science, and closely related areas would reside on the same continent. Teachers might say, 'Let's look at the new research frontier in sector F5.' Students could say, 'My mom works over there.'"

- Source: BBC

Blogrolls, Technorati, Blogstreet et al give you a rough idea of (some of) the people involved or interested in an area. But wouldn't it be good to be able to see what other things people were blogging about (and see maps of concepts in the same continent)?

p.s. Borner's PNAS article here

p.p.s. No. Borner isn't my mother.