Static, RIP, EIGRP, OSPF, BGP, IBGP, IS-IS and any other routing.
You should be able to redistribute the default route from OSPF to BGP. Is the default carried in OSPF as an external route (LSA type 5)? If so, it will not be redistributed into BGP unless explicitly configured (ie: redistribute ospf <process-id> match external). Default-information originate is also require in this case.