Bill Leisner writes. Sometimes people enjoy reading what he writes. Sometimes (though not terribly often) people pay him for writing it.
Stuff he's been paid for writing includes the Star Trek novels The Shocks of Adversity, Losing the Peace, and A Less Perfect Union (in the collection Star Trek: Myriad Universes: Infinity's Prism), as well as stories in the ReDeus shared-world anthologies Divine Tales, Beyond Borders, and Native Lands.
Stuff he doesn't get paid to write? You're looking at it.