You can also use a spell storing weapon to cast beneficial spells on your party members, but they take a little damage when you hit them. You can put a level 0-3 spell with Target: You into the weapon then hit your buddy. He takes damage and he gets the benefit of the spell. You can automatically touch willing targets as part of spellcasting; your DM may allow you to automatically hit a willing target, too. You can inflict nonlethal damage with a spell storing weapon; depending on your DM, this should also discharge the spell.
Here's a list of candidate spells for your spell storing weapon consisting of level 0-3 Player's Handbook spells with Target: You
Alter Self
Arcane Sight * 375 gp
Blink * 375 gp
Comprehend Languages * 25 gp
Disguise Self * 25 gp
Divine Favor * 25 gp
Entropic Shield * 25 gp
Expeditious Retreat * 25 gp
False Life * 150 gp
Find Traps * 150 gp
Glibness * 525 gp
Invisibility Purge * 375 gp
Know Direction * 12.5 gp
Longstrider * 25 gp
Meld into Stone * 375 gp
Mirror Image * 150 gp
Read Magic * 12.5 gp
See Invisibility * 150 gp
Shield * 25 gp
Speak with Animals * 525 gp
Speak with Plants * 1,000 gp
Tree Shape * 150 gp
True Strike * 25 gp
* Scroll available in DMG list
My favorites: Divine Favor (with PH errata, up to +3 attack and damage), Invisibility Purge, True Strike, Mirror Image.
Your fighter buddy with Power Attack would love to have a True Strike spell so he can Power Attack all the way for a big damage bonus but still have a good chance to hit his target. Give him the spell storing weapon and he can use it whenever he needs it. (Especially nice if he also has Quickdraw.)
It's nice to be able to plop a See Invisibility on your archer buddy for those pesky Improved Invisible spellcasters. It's a whole lot cheaper than True Seeing.
You can hit your buddy with False Life then cure the real damage, then he has temporary hit points equal to 1d10 +1 per caster level (maximum +10) for 1 hour/level.
A gauntlet is probably the best weapon for this trick. It doesn't do much damage (1d3 Bludgeoning, 20/x2) and it can be worn while your hand is holding something else. Depending on your DM, you might be able to wear a gauntlet over magical gloves.