Stuff portable hole into bag of holding.
(Done this. It was everything I thought it could be.)
Use unseen servant to randomly open doors in an area. Than when you go in invisibly, they just think that it's "that wonky door".
Use an unseen servant to rattle chains etc. to keep then enemy from sleeping soundly. The next day many of them have fatigue penalties.
Have them break tindertwigs in places with lots of flammables.
Send them to retrieve the MacGuffin while you're fighting the bad guys.
Use Share Spells to put it under the control of your familiar. That way they can do the things that need hands.
If you put a study base on a tower shield, then an unseen servant can drag it around and position it for you.
Reloading guns and crossbows.
Fetching dropped weapons - pair this with somebody with high disarm.
Spread dust around to find an invisible opponent.
Unseen Servant + Dancing Lights = instant haunting. Even better with Ghost Sounds.
- Pull down someones pants during fight
This one won't work, because that's the Dirty Trick maneuver. It requires an attack roll. Unseen Servants can't make attack rolls.
Sometimes if we're not going to be moving fast, I'll have unseen servant up before we get into combat. I give it a potion of cure and instructions to feed it to any of the party who go down.
Could it take out the arrows of someone's equipped quiver?
Probably not. That's very close to a steal maneuver. Although it does bring up the question of what counts as an unattended object.
Modesty preserver - holds up a towel or blanket when you're bathing.