Chegg, the textbook company, reportedly purchased lecture notes and study guide service Notehall, according to TechCrunch. TechCrunch also says that Chegg is considering an IPO, a wise move for a company that has received $219 million in financing and had revenues of $130 million in 2010. Notehall was founded in 2008 and went through the Dreamit Ventures incubator program.