Celtic Heroes

I as a warrior would like to know what warriors are good for in bossing other than tanking. I just want to know if warriors are actually usefull as a DPS compared to other DPS focused classes or is there other usefull ways a warrior can participate in a boss fight?

Depending on the boss, you can kite instead of tank. But if you already have somebody tanking the boss, the other warriors can be responsible to take care of the adds, especially keeping adds off of druids. Having taunt is useful in this situation since it will help you to pull a mob off of a mage (or others) that decides to hit the add. When there are no adds, keep shatter on the boss. Everybody likes that. Bash is also useful thing on bosses but sometimes is resisted a lot. Other than the things I mentioned, yeah you are just a bad rogue.

To keep adds away, warcry is better than taunt (i always use lvl 1 warcry when they call adds, gets them to me)
To beat other classes on bosses is pretty tough, requires very strong gear, its very rare to see someone gets kill on hrung for example (someone uploaded a screenshot once), but we do what we can, we cant have all warriors as tanks, its not our 'natural role', waste of class if it would be that way.

warriors have some skills that are really important in a boss fight (besides tanking skills):
shatter: very impotant!! increases the dmg of all meele classes.
shield bash: you can interrupt the strongest (aoe) skills of the boss.
defensive formation: also helpful in the lock grp to stay alive when the boss calls adds or the tank looses aggro.
also a warrior can have high dps. not as high as a rogue but you can outdps some rangers