Here's a poorly done diagram of the networks:

Internet<---->ROUTER 1<---->LAN 1<----->ROUTER 2<------>LAN
2<---->ROUTER 3<---->Internet

LAN 1 IP: 192.168.1.0/24
LAN 2 IP: 192.168.2.0/24
ROUTER 1 (LAN): 192.168.1.1/24
ROUTER 1 (WAN): 66.x.x.x/8
ROUTER 2 (LAN): 192.168.2.2/24
ROUTER 2 (WAN): 192.168.1.2/24
ROUTER 3 (LAN): 192.168.2.1/24
ROUTER 3 (WAN): 66.x.x.x/8

ROUTER 1: Linksys
ROUTER 2: Linksys
Router 3: D-Link

ROUTER 2 Routing table
Dest. IP Gateway Hops Interface
192.168.1.0 0.0.0.0 1 WAN
192.168.2.0 0.0.0.0 1 LAN

RIP is disabled on all three routers.
Some notes about Router 2:
DHCP is disabled
Set to Router mode (Not Gateway mode)
WAN Interface configured to accept incoming connections.

Sounds great, right? Well, it doesn't work. I can't ping from a host
on LAN 1 to a host on LAN 2 and vice
versa. Anyone have any suggestions? Awesome.