While many Internet-based mortgage ventures have floundered over the past year, surviving online financial services providers are betting that a strong mortgage facility is an important part of their strategy – whether they get it from another technology firm or a traditional lender. Two recent inter-species corporate marriages typify the trend. NetBank, a pure-play online banking business, recently acquired Market Street Mortgage, a conventional mortgage banking concern. Another web-based financial institution, E*Trade Bank, added mortgage