For regular rounds, I've been using PGA TourCaddie. But sometimes it's a bit cumbersome and takes time to adjust to my exact position. But overall I love it. Too bad I can't use it in more competitive situations :( I have't bought a set of the range finder/binoculars yet -- the prices are still too high for my liking.
@TarHeel: For me golf is still pretty relaxing but I like a little competition as well. Getting carry yardages/distances has helped tremendously for my, often poor, course management skills and my overall enjoyment. I'm occasionally breaking into single digit (+) scores these days and I think a big part of it is my mental preparation before a shot (e.g. just getting my number, picking a club, etc). I used to keep track of which club used and the conditions right on my scorecard, but that's a losing battle b/c either you turn in the card or the pencil marks get smudged.