JohnGolt

On April 10th 2012 IndexTank will shut down their servers. I suggest to build a list of IndexTank compatible API companies.

Open Source Version: https://github.com/linkedin/indextank-engine

Searchify: http://www.searchify.com/ (Running the full open sourced IndexTank Search as a Service API)

IndexDen: http://indexden.com/ (IndexTank Compatible API - builded on top of Sphinx Search)

HoundSleuth: http://www.houndsleuth.com/ (IndexTank Compatible API)

IndexTanktoGO: http://launch.indextanktogo.com/ (IndexTank Compatible API)

Probably some more companies should be mentioned here.