Based on the Marvel Previews #83, July for September 2010, I'd say you need to pre-order the following books in order to keep up with Spider-Man.
Core Titles
Amazing Spider-Man #642
Amazing Spider-Man #642, variant cover by John Romita SR
Amazing Spider-Man #643
Amazing Spider-Man #643, Super Hero Squad variant
Amazing Spider-Man #643, variant cover by Phil Jimenez
Amazing Spider-Man #644
Amazing Spider-Man #644, variant cover by Chris Bachalo
Spider-Man / Fantastic Four #3
Spider-Man, Marvel Adventures #6
Spider-Man: Back In Quack #1
Ultimate Spider-Man #14
Web Of Spider-Man #12
Guest Apps
Amazing Spider-Man Presents: Black Cat #4
Avengers & The Infinity Gauntlet #2
Avengers #5, regular cover
Avengers #5, super hero squad variant
Avengers, variant cover #5
Avengers: The Children's Crusade #2
Avengers: The Children's Crusade #2, Travis Charest variant cover
Heroic Age: Heroes #1
Heroic Age: One Month To Live #1
Heroic Age: One Month To Live #2
I Am An Avenger #1
Marvel Universe Vs. The Punisher #3
Shadowland #3
Shadowland #3, variant cover
Ultimate Mystery #3
Reprints
Acts Of Vengeance Omnibus HC, Alan Davis cover
Acts Of Vengeance Omnibus HC, John Byrne cover, direct market only
Marvel Adventures Spider-Man: Amazing Digest TPB
Marvel Masterworks: Marvel Team-Up Vol. 1 HC
Marvel Masterworks: Marvel Team-Up Vol. 1 HC, variant edition
Marvel Zombies Return TPB
Spider-Man Magazine #13
Spider-Man: Fever TPB
Spider-Man: The Gauntlet Vol. 2 - Rhino & Mysterio TPB
Spider-Man: The Gauntlet Vol. 5 - Lizard Premiere HC