Jason, you are exactly right. Suppose your ASBR is 10.0.0.1, and it has a default route in its RIB (it doesn’t matter whether that route came from EIGRP, or is a static route). From the ASBR, under your OSPF process, you would issue
(config-router)#default-information originate
Now, if you went to another OSPF router in the same area as the ASBR, you would see the following in its routing table:
Gateway of last resort is 10.0.0.1 to network 0.0.0.0
O*E2 0.0.0.0/0 [110/1] via 10.0.0.1, 00:00:01, FastEthernet0/0
So the ASBR is advertising an External Type-2 route by default to OSPF (using a Type-5 LSA).
By the way, the ASBR doesn’t have to have a default route in order to do this. If you modified the command just slightly with
(config-router)#default-information originate always
the “always” keyword will have the ASBR advertise a default route to OSPF whether or not the ASBR actually has a default route of its own.