I think they should be useful in minor ways (and when I DM, they are).
My lowly 2nd level wizard was in a party advancing down a maze of dark, twisty cavern corridors. We had reason to beleive an ambush had been prepared for us so we were moving cautiously. When we got to approach a 15x15' juncture with a 90 degree bend I was pretty sure something was about to happen.
So here's what I did;
I tossed a lit torch into the juncture, illuminating it.
I cast prestidigitation to create a mirror on the far side of the torch, angled so we could see around the corner before entering.
Later, after we moved on, I figured since the prestidigitationed 'pseudo object' lasts around an hour, I picked it up with mage hand and held it in front of us to check around corners whenever there was a sudden turn.
I'm usually the DM and I have to say, I kinda had to fight for that bit, because the guy that was DMing didn't think 0-level spells were meant to be useful at all.
In another adventure, one NPC was holding another npc hostage, with a poisoned handcrossbow cocked and ready. But (the villian) was negotiating with the players, so he was a bit distracted. One of the players cast mage hand from a hiding place to lift the bolt out of the string (thus disarming the weapon). As a DM I allowed that- it seemed really clever.
Mend seems to get used a lot in my campaigns as well.
