Here's what I've got so far for the alternates --
NFC ALTERNATES (will be updated with more names)
QB -- Drew Brees, Jon Kitna, Jeff Garcia
RB -- Edgerrin James (first), Clinton Portis (second), Frank Gore, Ryan Grant
FB -- Mike Sellers (first), Mike Karney, BJ Askew
WR -- Plaxico Burress (first), Roy Williams, Greg Jennings, Joey Galloway
TE -- Jeremy Shockey (first), Donald Lee, Bubba Franks
OT -- Chad Clifton (first), Bryant McKinnie (second), Jordan Gross (third)
OG -- Larry Allen (first), Chris Snee (second), Mike Wahle (third)
C -- Scott Wells, Dominic Raiola
DT -- Darnell Dockett (first), Shaun Rogers, Bryant Young
DE -- Trent Cole (first), Michael Strahan (second), Will Smith (third)
ILB -- Nick Barnett (first), EJ Henderson (second), London Fletcher (third)
OLB -- Greg Ellis (first), AJ Hawk, Ernie Sims
CB -- Charles Woodson (first), Nate Clements, Mike McKenzie
SS -- Roy Williams (first), LaRon Landry (third)
FS -- Brian Dawkins (second), Nick Collins (third)
P -- Mat McBriar (first), Donnie Jones (second), Jeff Feagles (third)
K -- Ryan Longwell (first), John Kasay (third)
ST -- Keith Davis (first), Heath Farwell (second)
KR -- Rock Cartwright (second), Nate Burleson
AFC ALTERNATES (will be updated with more names)
QB -- Derek Anderson (first), David Garrard (second), Carson Palmer (third)
RB -- Fred Taylor (first), Willis McGahee (second)
FB -- Greg Jones (first), Lawrence Vickers (second)
WR -- Chad Johnson (first)
TE -- Kellen Winslow (first)
OT -- Joe Thomas (first), Marcus McNeil (second), Levi Jones (third)
G -- Eric Steinbach (first)
C -- Kevin Mawae (first), Nick Hardwick (second), Nick Mangold (third)
DT -- John Henderson (second)
DE -- Aaron Schobel (first), Mario Williams, Elvis Dumervil (fourth)
ILB -- Mike Peterson (second)
OLB -- Terrell Suggs (first), Keith Bulluck
CB -- Rashean Mathis (first), Nnamdi Asomugha (second), Dre Bly (third)
FS -- Will Demps, John Lynch (third)
SS -- Kerry Rhodes (third)
P -- Mike Scifres (first)
K -- Shayne Graham (first), Kris Brown (second), Phil Dawson (third)
KR -- Leon Washington (first), Darren Sproles (second), Ted Ginn (third)
ST -- Gary Stills (first)
I'm still looking for alternates from these teams --
NFC -- Chicago, Atlanta
AFC -- (more Buffalo?), New England, Indianapolis, Pittsburgh, (more Oakland?) and Kansas City
I'm getting a little suspicious of two of the Packers' alternates, Ryan Grant and Greg Jennings, since there are now four alternates listed at those positions. Normally, there are three alternates named at each position. There might be others in line after them (in case none of the alternates can go), but they're not usually named as alternates right away.
