Living Greyhawk has a
free book sample that includes the Leech Ghost Skill spell, which allows you to use a ghost's skill ranks instead of your own.
Dragon Magazine #335 offers Loresong, a 1st-level bard/sorcerer/wizard spell that allows you to select one skill to use untrained. It also gives a small bonus to that skill, so you have a chance at it. Unfortunately, it can't be cast on allies, requires 1 minute to cast (!!!), and lasts only 1 round/level.
Wieldskill, cleric level 1, in Magic of Faerun, and Player's Guide to Faerun. Lets you pick 1 skill and make untrained checks with it.
Understand Device, cleric level 3, in Magic of Faerun, and Player's Guide to Faerun. Lets you make untrained Disable Device checks. I have
no clue as to why someone would choose this limited level 3 spell over the unlimited level 1 Wieldskill spell.
Find Traps from core = You can use the Search skill to detect traps just as a rogue can.
Appraising Touch from the Spell Compendium
sorta removes the limitations of the appraise skill for the untrained.