I'm kind of amazed that these don't seem to be in here already. They're staples for many of my characters (if they can't generate a similar effect themselves).
Third Eye Freedom (MIC, 2600GP), face slot: Once per day, as an immediate action, gain Freedom of Movement for one round.
Scout's Headband (MIC, 3400GP), Head slot: Allows you to flush out all of the item's daily charges to gain True Seeing for one minute. Standard action activation. Can spend fewer charges to gain lesser vision-based benefits.
Least Weapon Crystal of Revelation (400 gp): Invisible struck target surrounded by glowing aura for 1 round. Give one of these to the guy in your party who has blindsight/blindsense/etc and everyone else can free-ride on his ability, and spend their resources on something else.
Death Ward (MIC): +1 armor enhancement. Once per day, ignore Death effects, energy drain and negative energy effects as an immediate action.