Are there any professional players(hopefully with literature) that were known for their ko fighting prowess? Looking small on the board but having just endless threats to make at opportune times? Or does this sort of thing wash out at certain level of play?

Cho Chikun was involved in more than an average number of long cycle games.

That depends somewhat on how the opponent plays, no?

A modern player who is solid and thought to be very good at ko is Xie He. Some of the more drawn-out games with long or multiple kos date from an era when time limits were longer, though. If you want more accurate play some of the classical games might be better.

Go Seigen was known for being strong at ko (and everything else too!). There was a nice quote in Fairbairn's Kamakura along the lines of the game recorder on noticing Go's uncanny ability to win every ko fight he started and wondering what insight Go could share as to his skill here, to which Go nonchantly replied "I count threats".

A collection of pro games with interesting kos (registration required to replay, but you could look up games elsewhere):

http://gobase.org/studying/gallery/?id=ko

One of the famous old players (Dosaku?, Shusaku?, ???) said something to the effect that he didn't worry about his groups because if one got in trouble he could always make it live in ko. That would indicate confidence in ko fights.

I was thinking about this question as I wrote it. In some cases two players like playing ko's so they play ko's together in an extended fashion, when in fact there are alternate plays that would give the same or similar results, but in general I would say it does not take two to initiate ko.

As someone else noted in another recent thread... a ko fight is nothing more than offering a trade. One wins the ko and the other gets two moves in a row elsewhere. You just have to choose which you think is bigger.

Watch for Luo Xihe 9p. He's known for being particularly devious with ko battles. In fact, one tournament he won -- I believe it's Samsung cup -- he was incredibly crazy with ko battles to the point that he was called "King of Ko". Of course, you don't see Luo Xihe around much these days.

Now what about literature. It seems there is a book "Get Strong at Ko Threats""

http://senseis.xmp.net/?GetStrongAtKoThreats

There must be something a little more extensive about it somewhere.

That's a joke page on SL. All About Ko is a real book. I think it's pretty good, but it has some advanced material. That being said, the topic is not so easy.