Alamo is the one at Downtown Disney.
There's another Alamo/National office (DD location doesn't have National) at the Desert Palm Inn on Katella, right behind the Lion King parking lot. They have a shuttle to take you back, not sure if they'd pick you up if you called. Probably so, they were really nice when I returned a car there. There used to be an
Avis at the Best Western Park Place Inn on Habor, but I don't know if it's still there. Then there's an Enterprise near the Convention Center and they offer the pick up service.
Here's what I found when searching Yahoo Travel for locations near
Disneyland
700 WEST CONVENTION WAY (0.34 MI)
1700 HARBOR BLVD (0.23 MI)
711 WEST KATELLA (0.07 MI)
2132 SOUTH HARBOR BLVD (0.68 MI)
777 CONVENTION WAY (0.32 MI)
200 WEST KATELLA AVENUE (0.57 MI)
711 WEST KATELLA (0.07 MI)