Based on the Marvel Previews #78, February for April 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 #628
Amazing Spider-Man #628, Iron Man by Design variant
Amazing Spider-Man #629
Amazing Spider-Man #630
Amazing Spider-Man #630, villain variant
New Avengers #64
New Avengers, Marvel's Greatest Comics #1
Peter Parker #2
Siege: Spider-Man
Spider-Man: Fever #1
Ultimate Spider-Man #9
Web Of Spider-Man #7
Guest Apps
Civil War, Marvel's Greatest Comics #1
H.O.H. #1
H.O.H. #1, variant
H.O.H. #2
New Avengers: Luke Cage #1
Wolverine, Marvel's Greatest Comics #66
Reprints
Infinity Gauntlet Premiere HC
Infinity Gauntlet Premiere HC, variant edition
Marvel Adventures Spider-Man: Peter Parker Vs. The X-Men Digest TPB
Punisher: Dead End TPB
Spider-Man: Died In Your Arms Tonight TPB
Spider-Man: The Gauntlet Vol. 2 - Rhino & Mysterio Premiere HC
What If? Secret Invasion TPB
X-Men: Inferno Crossovers HC