Both GradeGuru and Notehall have support from academia. GradeGuru was a 2010 CODiE Award Finalist in the Best Educational Use of a Technology Device category, which was judged by a professor from the State University of New York, a professor from the College of the Canyons in California and an assistant principal from a Georgia high school. CODiE Awards are awarded by the Software & Information Industry Association to honor innovative products and services. Notehall has an academic advisory board made up of two professors from the University of Pennsylvania and one from the University of Arizona.
Not everyone is happy with note-taking businesses: Some university administrations and textbook publishers are crying foul over these businesses.
In Gainesville in 2008, e-textbook publishing company Faulkner Press, on behalf of UF Professor Michael Moulton, sued Class Notes, which owns the brick-and-mortar store Einstein's Notes. The lawsuit claims that Class Notes violated copyright laws by selling copies of notes from Moulton's lectures without his permission.
But Kenneth Hartmann, a lawyer representing Class Notes, said the materials published by Class Notes consist of "facts not original to the professor."
"Just like multiplication tables, those facts do not belong to the teacher just because he taught a math class or wrote them down, and they are not subject to protection under copyright."
That case is pending, and the trial is set for August.
Some schools have developed policies in an attempt to regulate the businesses. The University of Michigan, for instance, has a policy that requires commercial note-takers to notify the Office of the Provost and get permission from the instructor of the course.
These services also raise concerns with some professors, such as Dr. Richard Lutz, a UF marketing professor. "I think that there are too many students who just use those as a crutch or as a substitute from either attending class or watching it on the Internet and taking their own notes," said Lutz, referring to UF courses that are taught online.
Founders of both GradeGuru and Notehall say their sites are meant to be a supplement for students who are serious about their studies.
"GradeGuru is not supposed to be a substitute for students taking their own notes," said Sawtell. "It's supposed to be an additional support." Based on her company's research, Sawtell added, students who use GradeGuru don't attend class any less.
Conway said of Notehall, "We're not a way for students to cut corners."
Brennan Casey, a photography major at the University of Arizona, said she sometimes buys notes from Notehall because she likes to cross-check them with her own notes, in case she missed some information during the lecture. Most of the time, however, she chooses to sell her notes. The 21-year-old senior has been selling notes on Notehall.com since 2009 and has made close to $2,000.
"I was getting paid to basically do homework," Casey said.
She's found that selling her notes online has actually helped her grades. She said because she has to pay close attention to the notes she's writing and then type them up for the website, it's helped her remember the material better. While she was taking notes for Notehall, she earned a 4.0 GPA two semesters in a row for the first time in her college career.
Regardless of the ethical and legal concerns surrounding the topic of businesses selling class notes to students, Casey said she will continue to sell her notes on Notehall.com as long as students keep buying.
And as long as there's a need for these note-taking services, said Lutz, they're here to stay.
ABCNews.com contributor Amy Rigby is a member of the University of Florida ABC News on Campus bureau.