Based on the Marvel Previews #95, July for September 2011, I'd say you need to pre-order the following books in order to keep up with Spider-Man.
Core Titles
Amazing Spider-Man #669
Amazing Spider-Man #669, Marvel Architects Sketch variant cover
Amazing Spider-Man #669, Marvel Architects variant cover
Amazing Spider-Man #670
Art Of Spider-Man Classic HC
Spider-Man, Marvel Adventures #18
Ultimate Spider-Man #1
Ultimate Spider-Man #1, variant cover Sara Pichelli
Ultimate Spider-Man #2
Guest Apps
Avengers #17
Avengers #17, Marvel Architects Sketch variant
Avengers #17, Marvel Architects variant
Captain America Corps #4
Fear Itself #6
Fear Itself #6, Marvel Architects Sketch variant
Fear Itself #6, Marvel Architects variant
Fear Itself #6, Mike McKone variant
Fear Itself #6, Stuart Immonen variant
FF #9
FF #9, FF 50th Anniversary Variant
Herc #7
Herc #8
Marvel Universe Vs. Wolverine #4
Moon Knight #5
New Avengers #16
New Avengers #16, Marvel Architects Sketch variant
New Avengers #16, Marvel Architects variant
New Avengers #16.1
New Avengers Annual #1
X-23 #14
X-Men #17
X-Men #17, FF 50th Anniversary Variant
X-Men #18
X-Men #18, Marvel Architects Sketch variant
X-Men #18, Marvel Architects variant
Spin-Offs
Venom #7
Reprints
Essential Defenders Vol. 6 TPB
Essential Spider-Man Vol. 3 (All-New Edition) TPB
Essential Spider-Man Vol. 4 (All-New Edition) TPB
Marvel Masterworks: The Amazing Spider-Man Vol. 6 TPB
Marvel Masterworks: The Amazing Spider-Man Vol. 6 TPB, variant edition
Marvel Super Stars Magazine #7
Spider-Man: The Return Of Anti-Venom Premiere HC
Spider-Man: The Vengeance Of Venom TPB
Spider-Man: With Great Power Comes Great Responsibility #6