I can vouch for a bunch of these myself. The Doctor Who collections are a lot of fun (although Who fandom folks are likely well aware of them already). The assorted Marvel anthologies are fun, and Finding Serenity is something that every Whedon fan should own.
Buffy: The Deathless would have made a damned fine episode during Season 3, and features a Tuckerization of
All of the Trek books are great, but I'm partial to the Gorkon books.
And for fans of Andromeda (or for fans of Andromeda's first two seasons, because realistically, there are no fans after that), the Andromeda novel he wrote is a great prequel to the series (and the first Krad book I ever read).