Re: better than carpet!
I recently did the bow interior are of my boat with rustoleum and walnut shells (sold inexpensively as blasting media - I also had some on hand) and part of the main compartment floor in the rest with ultra-tuff water-based polyurethane non-skid.
I am going to go with the rubberized ultra-tuff non-skid because we spend a LOT of time barefoot, skiing, etc... in the boat and it's a little easier on the feet as well as being made to stay wet.
I will say the the cheap combo of walnut shell and rustoleum worked great as well and also appears to be quite durable (we often have skiis, maybe spare prop, anchor, etc... riding on that part), not slippery, and easy on the feet. On a budget I would go with it in a heartbeat. I also wouldn't hesitate to use walnut shells with an even more durable two-part paint after the way it turned out..
The ultratuff is a bit more expensive (ok a lot at something like 70 a gallon), and is made and used for things like the concrete decks at water parks, etc... The version with the compounded rubber in it is what we tried and it works great. We did light grey and were able to match the color with rustoleum white tinted with grey on the interior sides. I'm going to splatter paint over it to break up the grey and am a little worried about the splatter paint adhesion, but we'll see how it works once it's done...
Hope this is helpful.
Oh, I brushed and rolled both on... with walnut shells, laid a heavy coat of paint down in the areas I wanted the non-skid coating (taped off) and then sprinkled a heavy layer of ground shells on it and let it dry. after that vacuumed the loose shells off the paint, removed the tape and put another heavy coat of the same paint over the top... On the tuffcoat, get the textured roller they sell for use with it - it makes it a lot easier to get it to lay down right. imho