Here's the list of aircraft you're expected to know for the Aircraft Recognition Quiz for En Route. If you take Basics, you'll have covered about 3/4 of these in a separate section (they provide you with flash cards).
Like Roddy said, visual recognition isn't very important in En Route; you're just expected to know aircraft ID, number of engines, engine type, weight class, and approximate climb rates and speed (for comparison, e.g. a Gulfstream climbs faster than a Beechjet). There's also a computer lesson that you'll take that covers them -- and they'll give you a copy on CD. Can't provide course materials here publicly, but don't worry, you'll have plenty of time to study it.
Don't worry too much about the variants, like the difference between a 777-200 and 777-300. In En Route, it's generally not a big deal. There are a few exceptions, like 737-100s and -200s underperforming later models, but you'll get to know them. If you're familiar with a few coming in, you'll have a nice head start.
Someone else can jump in on what else needs to be known for Terminal.
SINGLE ENGINE PISTON
Cessna 172 Skyhawk - C172
Cessna 182 Skylane - C182
Cessna 210 Centurion - C210
Piper Cherokee - PA32
Piper Comanche - PA24
Beechcraft Bonanza - BE36
Cirrus SR22 - SR22
Piper Malibu - PA46
TWIN ENGINE PISTON
Piper Seneca - PA34
Piper Navajo - PA31
Beechcraft Baron - BE58
Cessna Golden Eagle - C421
TURBOPROP
Single engine
Cessna Caravan - C208
Pilatus PC-12 Eagle - PC12
Twin engine
Dehavilland-8 (A, B and C models) - DH8
King Air - BE9T (also BE10 and BE20)
Beechcraft B1900 - B190
Saab SF34 - SF34
Fairchild Swearingen Metro - SW4
Dahavilland Dash 8 - DH8D
Super King Air - B350
Cessna Conquest - C441
Four engine
C-130 Hercules - C130
TURBOJET
Single engine
F-16 Fighting Falcon - F16
Cessna Citation Mustang - C510
Eclipse 500 - EA50
Twin engine
CRJ-200 - CRJ2
Embraer E-190 - E190
Embraer E-145 - E145
CRJ-900 - CRJ9
Boeing 717-200 - B712
Boeing 757-300 - B753
Boeing 777-200 - B772
T-37 - T37
Beechcraft Beechjet - BE40
Airbus 320 - A320
McDonnell-Douglas MD-82 - MD82
Boeing 737-800 - B738
Boeing 767-300 - B763
Cessna Citation X - C750
LearJet 55 - LJ55
Gulfstream 4 - GLF4
Talon AT-38 - T38
Four engine
C-17 Globemaster - C17
C-5 Galaxy - C5
E-3A Sentry - E3RF
Airbus 380-800 - A388
Airbus 340-300 - A343
B1 Lancer - B1
B2 Spirit - B2
Boeing 747-200 - B742
KC-135 Stratotanker - K35R
Eight engine
B-52 Stratofortress - B52