Based on the Marvel Previews #106, June for August 2012, I'd say you need to pre-order the following books in order to keep up with Spider-Man.
Core Titles
Amazing Spider-Man #691
Amazing Spider-Man #691, Lizard variant cover
Amazing Spider-Man #692
Amazing Spider-Man #692, decades variant cover A
Amazing Spider-Man #692, decades variant cover B
Amazing Spider-Man #692, decades variant cover C
Amazing Spider-Man #692, decades variant cover D
Avenging Spider-Man #10
Avenging Spider-Man #11
Marvel Universe Ultimate Spider-Man #5
Peter Parker, Spider-Man #156.1
Scarlet Spider #8
Sensational Spider-Man #33.1
Sensational Spider-Man #33.2
Spider-Men #4
Spider-Men, Deodato variant #4
Spider-Men, Pichelli variant #4
Ultimate Spider-Man #13
Ultimate Spider-Man #13, Granov variant
Web Of Spider-Man #129.1
Web Of Spider-Man #129.2
Guest Apps
Avengers Vs. X-Men #9
Avengers Vs. X-Men #9, variant cover "promo"
Avengers Vs. X-Men #9, variant cover Adam Kubert
Avengers Vs. X-Men #9, variant cover Avengers team
Avengers Vs. X-Men #9, variant cover Ryan Stegman, sketch
Avengers Vs. X-Men #9, variant cover Ryan Stegman
Avengers Vs. X-Men #9, variant cover X-Men team
Avengers Vs. X-Men #10
Avengers Vs. X-Men #10, variant cover "promo"
Avengers Vs. X-Men #10, variant cover Avengers team
Avengers Vs. X-Men #10, variant cover Nick Bradshaw, sketch
Avengers Vs. X-Men #10, variant cover Nick Bradshaw
Avengers Vs. X-Men #10, variant cover X-Men team
Deadpool Kills The Marvel Universe #1
Secret Avengers #30
Spin-Offs
Venom #22
Venom #22, variant cover Michael del Mundo
Venom #23
Venom #23, variant cover Humberto Ramos
Reprints
Essential Warlock Vol. 1 TPB
Ultimate Comics Spider-Man: Death Of Spider-Man Omnibus HC