I used the flush-mount Aquameter Skipper in my Guillemot 18. It has the same card as the Skipper that Joe Greenley posted photos of a week or so ago in his post about his low-profile compass mount.

http://www.kayakforum.com/cgi-bin/Building/index.cgi/read/58125

I stripped in a flat platform for my compass, cut a hole for the bottom of the compass to drop into, weatherstripped on top of the flat, and screwed the compass to the flat on my Guillemot:
http://www.geocities.com/shawnkayak/guillemot/index.html
(pictures all the way down the page show the recess)

Here is my compass mount for the cheap Ritchie X-10 Sport compass:
http://www.geocities.com/shawnkayak/compass/

: I'm not sure though if it's really good way to go or not. I don't have a lot
: of sea experience and I may be missing something here.

#1 Priority: buy a compass whose card you can read easily, and you like the look of the numbers. I like the Aquameter Sailor II like Pete R. uses, but I don't like the way it cuts off the 0. That compass shows 180* as 18. I don't like that, but it's a personal preference thing.

: It seems to be the standard removable compass for sea
: kayaking.

Are you sure you need a removable compass? I've never lost or damaged mine, and I'm pretty hard on boats. I'm an instructor and I frequently do boat-over-boat rescues--the compass is far enough forward on the foredeck to be safe. I'm also a navigation junkie and kayak geek who likes to look down at my compass every time I'm paddling (it's not a bad habit to be in)

Shawn