Ok, I will bite. This is a "out of date" HFT strategy that uses "rebate trading" on AMEX to make some decent rebates. Back in 2004-2005, there were a list of names that ARCA maintains that there is 0.0 (zero) cost for taking liquidity, and something like 0.2 cents for providing liquidity. So a very simple strategy would be (again, this is before RegNMS, but obviously the orders can be sweeped).
a) Put on order on a particular ticker. Assuming the "trend" is not against you (momentum analysis).
b) Monitor the broad market and correlated symbols (correlation analysis), assuming nothing severe happens, keep the order, otherwise, cancel. And as necessary, replace the order.
c) Immediately after fill (assuming there is enough order queue after execution, otherwise the order shld have been cancelled), sell (assuming it was buy), or buy cover (assume it was sell short), at the same price.
d) Collect rebate.
I have seen a few guys making a few thousand / day doing exactly like this on AMEX (which eventually discontinued this "special list"), obviously not *all* the profits come from rebates, but if you think about it carefully, the "rebates" provides a nice fat little "add on" in addition to any profits. They would put on 5-10k blocks, and just wait. Again, this only went on for a few years, and would seems to be "gaming the system", but heck, there is nothing wrong with making 500k-low few M for doing something fairly simple for a while.