I don’t have specific resources to point out, but if I were looking, I’d check a Google News search for “online bingo” in quotes. http://www.dot-bingo.com/ has a news archive that stretches over a couple of years, but you might be able to figure something out from it.
Someone willing to do the research on the industry could make quite a large site about the online bingo industry. It hasn’t received nearly the attention (from an industry perspective as opposed to an advertising perspective) as say the online poker industry.