Graffiti (by S. Fajtlowicz) and Graffiti.pc (by E. DeLaViña) are computer programs that produce conjectures in graph theory.
See Doug West's web page, "Some Conjectures of Graffiti.pc (2004-07)," and the more recent, "Bibliography on Conjectures, Methods and Applications of Graffiti," which includes papers through 2011.