I generally browse when i upload and then again if i check back later on what people have said about it.  I do pretty much the same as you tom - i go through the first 4 or so pages and i tend to leave comments on things i think are good, if i have nothing to say but a "really cool shot, love it" kind of thing and there were about 10 people who left something similar i tend not to bother because i think whoever took the shot got the idea, that or i actually say why i like it because that is more useful to the photographer.
I also try to put something critical into the comment and will sometimes open up a shot i might not really like but know needs a bit more thought put into it just by looking at the thumbnail, you know the type of shot when you see it.  Even on stuff where there is limited things to pick up on for improvement i do make an effort to see past the initial "omg this is really cool i must post undying praise for it and turn a blind eye to problems in the shot".

If i were to continue on this train of thought i would go on to what i expect a comment to be like, but that isnt the remit of this thread ;) Oh yeah - and i only really do the photography galleries, i sometimes out of curiosity go look at the maya or 3ds max galleries - because that is where most of the really good 3d stuff is.

Oh and if you all have noticed my non-participation in the galleries, that is because i havent got a great deal of time to a)shoot/upload new picks b)browse the galleries right now.  I am currently really close to my dissertation deadline on wednesday so am basically doing that all day everyday now.

"In every colour, there's the light.
In every stone sleeps a crystal.
Remember the Shaman, when he used to say:
Man is the dream of the Dolphin"

Rich Meadows Photography