Simple but good article in the Dallas Morning News about the growth of advertising within niche social networks that “cater to specific interests, backgrounds, professions and age groups.”

Some good stats too:

“ Overall, ad spending on social networking sites is expected to grow 75 percent next year, to $2.1 billion, according to eMarketer, a research firm that tracks online advertising.

But smaller sites’ share of that money is growing. Of the $920 million spent this year to advertise on social networks, 8.2 percent went to niche sites, up from 7 percent in 2006, according to eMarketer. Next year, niche sites’ share of ad revenue is expected to grow to 10 percent, according to an eMarketer report released in December.”