Whilst I've been having to endure the increased loading times in Dawn of War Soulstorm, I've noticed that I'm pretty unproductive in these ever so common time wasters.
I seem to spend most loading screens cross armed biting my nails lost in thought, reading the manual for details, or walking off to find some new music to play. I'm going to mix things up from now on though with a doodle pad.
Remind me of the old cartridge days, no loading screen, just quick access gaming non stop for hours.

When I'm loading CSS or something, I usually read a book. Or draw. Or if its really long, I pull out my DS and pound through some Contra 4.

You're looking at it, right now I'm waiting for Galaxy city to load up on City of Heroes.

I sing demented songs, or I hum the game's main theme if it's good.

I got a printer, with paper inside, and some pencils. Otherwise I clean my screen every time a loading screen appears, rare though... since I sold my soul to get this PC.

Either read a book or annoy the dog (usually consisting of bonking him on the nose until he goes for my hand).

I tend to tap the sholder buttons in unison

I sit there patiently.
But in the case of things that take long times to load that others may not deem games that I use, (VirtualDub, Premeire Pro, 3Ds Max...) I may just go off and play a video game or walk away and go read or watch TV.

Protagonist:
Or if its really long, I pull out my DS and pound through some Contra 4.

Amen to that, brother. I do the same thing.

I go find the computer and wank-off ocasionaly.

No, but seriously, i'm usualy patient. Loading isn't much of a problem with me.

Jolly Madness:
I got a printer, with paper inside, and some pencils. Otherwise I clean my screen every time a loading screen appears, rare though... since I sold my soul to get this PC.

yay someone else who sold their soul for their PC, i dont really miss my soul do you?

to the topic tho - i usually either phase out and daydream on the few loading screens i have or if im on console i just slide me chair over (hail wheels) to the PC and check my MSN or something.

I also tend to play Phun, http://phun.en.softonic.com/ , when im waiting for stuff on my browser to load.
Anyone want to tell me what tags this forum uses for links and pictures etc?

Hum the countdown theme tune and see if i can guess when its just about to finish loading. Bada bada badadaa daaaaaaaaaaaa.......... you get my meaning

I sit and stare at the television screen; almost a vegetable. Or, if I'm in a 'productive' mood I'll catch up on webcomics.

Read a book or watch tv, depending what I am doing at the time.

For games with short load times I usually just fidget with the multitudes of crap on my desk. For long loads (or installations) I crawl into bed and grab the current book I be reading... Or try to rub one out.

I sit impatiently devising a strategy if needed.If not then I watch whatever animation is on the loading screen

I usually have Windows Media Player on most of the time so I just listen to music alot, I have to turn it off when the game actually loads up though.

If a book is nearby, read it. If not, I wonder to myself why optimization in a game hasn't turned into an essential task yet.
Well, I've become tolerant of loading screens though. Back when I was younger I was a lighter version of the Angry German Kid, constantly saying "Stop loading...now! Now! Stop loading!".

Sometimes I try to force persuade the game to load faster.... Doesn't usually work though.

It depends. If we're talking a console like waiting for Oblivion to load on my Xbox 360 I just stand up, stretch a little, and sit back down.

If it's a long loading PC game, and by that I mean Sims 2, and by that I mean always Sims 2; I read a novel, go out to a bar, pick up a woman, awkwardly forget her name the next day, eventually convince her she can do worse than marrying me, have 2 kids - name one after her father, God rest his soul - and adopt a puppy, explain to the kids that sometime doggies go to Doggy Heaven before scraping the carcass off the road, discover my wife is cheating on me, divorce, reconcile, and hopefully by the time our youngest has graduated high school I can sit down to the Sims 2 for a simulated life experience.

I w-- think I better keep it to myself...

I change the channel on my TV and watch some sort of Sitcom (I have a 360).

button mash and talk to myself in different accents and genders. i have MPD...

Sit patiently for about a second or 2, wondering what the world's coming to. Ah, the joys of console gaming...

I masterbate furiously like a necro in a graveyard. I collapse in a pool of my own sweat and pass out. Around the time I wake up again the game's loaded and I'm right to play, if still a little light headed.

EDIT

Crap, somebody else said wanking. I guess it's become a popular passtime on loading screens.

....... ok then.

Anyway I try to remember what game I am playing, and what I am doing in said game.

Terramax:
I w-- think I better keep it to myself...

Come on... admit it, I know what you were going to say... You watch the Golden Girls.

PurpleRain:
Crap, somebody else said wanking. I guess it's become a popular passtime on loading screens.

You're sitting alone in a chair with nothing to occupy your hands, it's gonna happen no matter how hard you fight it... Now not such a good idea at internet cafe's or the library though.

I usually flip through Surfin' the Highway or read some of whatever book I happen to be reading.

I usually stand up and stretch my back/neck/legs, or for the longer load times, I fire up my DS and play a little Metroid Zero Mission.

Khell_Sennet:

PurpleRain:
Crap, somebody else said wanking. I guess it's become a popular passtime on loading screens.

You're sitting alone in a chair with nothing to occupy your hands, it's gonna happen no matter how hard you fight it... Now not such a good idea at internet cafe's or the library though.

I found out the internet cafe one, the hard way. Get it... hard?

Note to self: die.

Mash all the buttons in hopes it does something. If not then stare blankly into nothing until a distraction or games loaded

I use this time to do my homework and listen to my iPod.

Back when I had a rock-buttom end PC (that took ages to load Warcraft III) I would just read or find a toy to fidle with (I'm easily amused).

Divinegon:
Stop loading...now! Now! Stop loading!".

Oh, sometimes it WOULD stop. and I mean STOP! That realy ticked me off

flick the switch on my vga splitter and check t'interwebs if i'm on the 360, or read if im on the pc.
i tell you, it sucks balls having a "slow" pc these days. when it takes 15-20 mins for bloody steam to load, let alone half life 2, it tends to drive you a bit nuts...

Edit
I'm quite drunk and more than likely over-exaggerating here...

I usually tap my fingers on the buttons of the controller in rhythm with whatever music is playing during the load or in my head. Or I just stare at the screen. I don't know if I'm thinking anything. Probably psyching myself up for whatever part of the game coming next.