seems like the vast majority dont anyone know which brokers are decent to good and pay interest on funds like IB does? IB pays like 5% on accounts over 100k sweet
fidelity has excellent sweep account options. better than ib for almost all situations. the straight up fido money market has similar rates to ib, fido offers tax free money markets with superior effective rates, and fido doesn't do the whole not paying interest on 10k ($500/year less in your pocket). just make sure you switch from the default sweep into the best option for your situation.
Ameritrade sweeps cash to http://www.reservefunds.com. Right now, about 4.35%. for commercial paper. Not a great rate, but Ameritrade tools are pretty good. Also, you can ACH in/out free (but there might be a max of ACHs per week). The treasurydirect.gov website works pretty good too (all ACH free, no commiss, $25/year total fees over 100,00).