I have a 3" model 65 that I keep in the truck.  I left the truck at the airport over the weekend, and took the gun out.  When I was putting it back today, I decided to unload it and dryfire a bit to see how it felt.  When I opened it, the cylinder would barely turn at all.  After I got it to turn, it felt like it was loosening up, but its still sticking pretty good, not nearly as loose as I remember my old 686 being.
Any suggestions as to what the problem may be?

I have no idea. Either it's just grunge or somehow the ejector rod might be bent.
Removing the crane and cylinder is pretty easy
(there might be a bit of locktite on the crane retaining screw). I strip my 686 down every few thousand of rounds or so and give the parts a thourogh cleaning and light coat of oil... the cylinder spins like a top.

Clean it and lube it lightly. Should work fine then.

First, what make? S&W and Tuarus both make a M-65.

Next, stop and carefully try to find out what is sticking. Until you know what and why there's little you can do.

Its a S&W.
I don't really know proper revolver terminology, but it appears that the ony thing that could be sticking is the spindle that the cylinder spins around.  Its not rubbing the frame or anything.

Okay, question 2. When the cylinder is open, does it spin freely?

nope, it sticks whether open or closed.

Depending on the time of manufacture, many of the later S&Ws...from the mid 1970's until the mid-late 80's...may have problems with crud blowing back into the cylinder/crane area. Combine this with a little oil and you get a paste-like gunk that will build up and even harden with time. Revolvers, while extremely reliable, are built to very fine tolerances, and it may not take much buildup to cause a problem. There were a few runs of M65 3in. guns that did not have enough tolerance in the relief cut for the extractor star, and these would lock up quickly if only a few flakes of unburned powder got under the star. S&W remachined those that were sent back and they ran fine.

If the crane/cylinder is clean and lightly lubricated and this is still happening, I would suspect the extractor rod or center pin. The rod can be straightened, but it should be by someone who knows what to do. The center pin is a different problem and, if faulty, should be replaced. Most probably though it just needs a thorough cleaning.

If it sticks while open, then it's possible that the extractor is bent, but I doubts it.

Get a good CLP that comes in one of the aerosol spray cans with the little straw like applicator. Push the extracor all the way out and spray it as it returns. Work the extrator in and out a half dozen times or so. Lightly spray both ends where the extrator goes through the yoke.

Chances are that will fix it for you.

If you find that the extrator binds or is hard to operate, then you need to get someone to take a look at it. That could well be a bent extrator.