I have not yet used any shouts in combat.

I kind of forget about them. I should use them more often.

But one concern about them, is whether they will also harm a companion fighting with my character?

I'm playing a non-combat character on Master. Shouts are an essential part of my strategy. You'd be surprised how often Unrelenting Force and Whirlwind Sprint can save your life. I use Kyne's Peace all the time on wolves, who just get irritating when you walk everywhere. Those are the only shouts I've learned so far and had a chance to use and I consider them pretty useful.

Personally I use the slow-time shout most often. Walking into a tight room filled with fire mages and dual-wielding with light armour? Helps a bunch to dodge those first few bolts and get in there and power attack them down fast.
Unrelenting force I use it high places, knocking things off a cliff never gets old.
Marked for death I definitely use on the elder/ancient dragons (I play on master difficulty and their fire breath one-hits you) anything to kill them fast.
Call Dragon when I'm up against 2 dragons and/or Call or Valour.
Throw Voice/Disarm/Dismay good for getting the hell out of somewhere quick.
Whirlwind Sprint because walking svcks + hidden ledges

Oh and sometime I use Clear Skies as the snow falling constantly in your face can be a bit of a handicap in a fight, especially when bandits are sniping you though the trees.

I use the life sense one constantly. On dragons or other bosses I may switch to Marked For Death. Otherwise, no.

I rarely use any other shouts. I have tried most of them. Many of them are lackluster. Frost Breath at rank 3 isnt even worth casting. Time Stop is usually meh except for puzzles. Etc.

But Aura Whisper? I love it. I love knowing where foes are, and it detects life, unlife, constructs, etc, all in one power. Its the best shout in the game.

I find myself only ever using 2 shouts. Ethereal and Unrelenting Force when im in high places. Ethereal because I am playing DiD (Dead is Dead) so I gotta be wary.

I use Aura Whisper all the time when in dungeons. It's just like a detect life spell.

I never use shouts. And the dragons are well made but they're not fearsome or dangerous, and they're annoying because you can't get tid of them quickly as they're mostly in the air.

I think I have the same experience as most- since the cooldown is so high, rarely remember to use them. I definitely agree with one of the above posters though: Fus Ro Dah -ing someone off a cliff NEVER gets old.

I use the "Marked for Death" shout pretty frequently...

Wearing the Amulet of Talos helps with increased cool-down time...it actually cools down pretty quickly..

What can you say, they're all very situational. Sure, you may never think to use Unrelenting Force in combat, but then you catch that one Dragon Priest standing with a 200 foot cliff drop behind him and it's suddenly the best thing in the world.

Or maybe you are the one at the top of a 200 foot cliff, looking down. Become Ethereal and just jump as far as you can.

Throw Voice is invaluable to sneak types. I don't even need to mention how valuable it is, but I will. It's super valuable.

Ice Form is like Mass Paralyze, but instant.

Marked For Death is one of my favorites too. Love using it to spite bosses and dragons.

I use Elemental Fury all the time in combat. It's excellent for melee characters.

Also, Become Ethereal is fantastic for base jumping: You can't die while ethereal so can jump off anything as long as you're still ethereal when you hit the ground.

There is a shout to make them land fyi ^^

And turn the difficulty up if its too easy

Marked for death, Ice form, slow time, throw voice are easily the best. Unrelenting force is good for a laugh now and again.

Well so far I've only found out where to get Ice, Fire and the animal calling one...and only ever unlocked force (I presume each dragon you kill unlocks a shout?) and only one word for each so far. Total noob, haven't done enough exploring to find shout words yet...

Can't believe there arent more votes for 'Slow Time'. Almost makes boss battles against mage type characters trivial for my One Handed warrior. Run in, Slow Time, I get about 5 critical hits in before he knows it and he's dead. Also use it against Dragons all the time. Slow time, charge in, get about 6 swings in.

Aye I really like that shout in a way, its like you get 'superhuman' speed you can control by slowing down everything else, can land a few good hits. Most people see it as useless because they think you get slowed down as much as the mobs do.

I only really use Dragonrend and Unrelenting Shout.

My destruction mage uses a few of them to stall for time when the enemies get too close, but the cooldown really does make it a "which 1 shout do you want to use for this fight". I'm also really disappointed that the storm shout hits friendlies. That almost makes it useless, because there's liable to be someone innocent within it's range no matter where you are, even if you don't have a companion. Although it does work in Blackreach.

I am really, really aggravated that one of the Fire Breath words is locked behind a Companions-only quest. I know that my mage character has no shortage of fire-making stuff, but I'm DRAGONborn... I should be good at FIRE!!!

I started a big Nord w/ a beard, fighter type. I have a feeling that shouting is going to come in handy for the crowd control with him.

I spam Ice form like nobodys business in mage forts.

Its almost SWAT like, except instead of flashbanging the room, I paralyze everyone in ice crystals.

aura whisper is my thief's favorite

If you use restoration magic then something like Unrelenting Force is extremely useful. Send your enemies flying across the room, in the time until they get back up you can heal up completely and reequip your shield.

I think that shouts are very underpowered, and the ones that are good take ages to charge.
for example Fire breath takes lots of time to charge and yet it's weaker than some magic spells.
Call storm is very powerful and nice but it takes years to recharge, so I rather would use different shouts than wait hours to finally be able to use different shout.

It is pretty cool... until you forget you left it equipped during battle and instead of "Fus Do Rah" 'ing that bandit off the cliff, you conveniently got rid of that storm cloud over his head...

The W key is too hard to reach