There are several options for carrying bikes with a RAV4: Inside the 
Car, Roof Rack, Trailer-Hitch Carrier, Spare Tire Carrier, or Trailer.  
Each has advantages and disadvantages.  In all outside-the-vehicle 
options, consider the ability to properly secure your bikes to prevent 
theft.

- Inside the Car -- One or maybe two bikes should fit in the back of a 
4-door RAV4 with the rear seats folded up, more easily with the rear seats 
removed.  If you need to carry more stuff or require the back seats for 
passengers, or if you have a 2-door RAV4, consider one of the 
outside-the-vehicle options.

- Roof Rack -- Only tall people should consider this, as the RAV4 (among
other sport-utilities) is already a tall vehicle, and access can be 
difficult.  Toyota sells a roof rack (about US$150).  Major aftermarket 
rack makers such as Yakima <http://www.yakima.com/> and Thule <http://www.thuleracks.com/> 
also make RAV4-compatible racks.  

Note: The Toyota factory roof rack accepts all Thule accessories, 
      including their bike carrier and all ski carriers.

Also, from John Fawcett <fawcett@gwis.com>:

"The RAV4 factory rack is the same size as the Thule rack system 
(20 x 30 mm) and will accept all Thule accessories.  Yakima now 
sells an adaptor called the 4H MightyMounts that are specially 
designed versions of the Yakima SnapAround that attach to factory-
installed roof racks and other non-Yakima rack systems such as the
Thule and other European standard 20 x 30 mm crossbars.

However, the Yakima Steelhead fork-mount bike rack will not fit the 
RAV4 factory rack. The Steelhead is designed to clamp/lock directly 
to a round bar. The new Thule VeloVise, a similar fork-mount bike 
rack is the only option I've found at this time."

- Trailer-Hitch Carrier -- If your RAV4 has the rear step bumper/trailer 
hitch, you can buy a bike carrier that utilizes the trailer hitch.  
These will hold 1 to 4 bikes.  You may need to remove the carrier to 
open the rear cargo door, although some of these carriers include a 
"swing away" feature.

- Spare Tire Carrier -- This option is a carrier for 1 or 2 bikes that 
attaches to the rear spare tire.  They usually attach to the tire via 
straps.  This is relatively inexpensive, easy to install, and does not 
impede access to the rear cargo area.  Consensus opinion and user
experience suggests that the rear door and the spare tire are sturdy
enough to carry bikes securely and without damage to the vehicle.

- Trailer -- You can always buy or rent a pull-behind trailer that can 
carry bikes, as well as other cargo.  The number of bikes that can be 
carried this way is limited only by the size of the trailer, and the 
RAV4's towing capacity of 1500 lbs (150 lb tongue weight).