this may be a stupid question but, aside from all the bugs associated with the companions quest-line, how do you know when you've completed their quests? do they give you fetch quests ad-nausea? or is there an end to it?

no one has an answer? the reason i ask is due to the fact that i've done a million fetch quests, then i seem to randomly get a quest to find a totem.

I would say that you completed the main companions quest after you have freed Kodlacs spirit and become harbinger. Of course you can continue to do random jobs after this but the main quest line is complete.

There will be quests that increase your wolf shouts but they are mixed in with the usual boilerplate stuff.

The quest line is largely over after you have become the new harbinger. Aela has three unique quests that she'll randomly give you when you ask for a job (they involve collecting totems), and the other two each have a "free me from being a werewolf" quest that will also show up randomly. If you've completed all of those your remaining options are all radiant quests (and curing yourself of lycanthropy, if you choose to do so).