I'm sort of obsessed with "useless" skills and I'm actually working on a detective with Item ID, Forensics, Tracking, begging, and a couple of other things just for fun. I have camping on my fisherman, again, for the fun of it.
Neither of these characters will ever do anything meaningful in combat, and I'm okay with it, but as I utilize these skills I wonder if we can't find ways to make them useful again. Like the way Evaluating Intelligence was reinvented to make spells do damage, perhaps something similar could be done with Item I.D. and Taste I.D.
For instance, right now Item ID gives an item's vendor price, and tells what a magical item will unravel into. Applications of this skill could provide a bonus to vendor sale prices (you can get more gold for garbage items if you're more knowledeable about what you have), additional turn-in points for goods that are tossed (this could be great, I think), and additional unraveling spoils for magical items. Adding % increases for all three of these could make this skill more valuable.
Taste ID doesn't do much at all right now except for detect poison in foods and identify potions. It happens that Cooking is also the least "valuable" crafting skill. Perhaps a solution would come by combining Cooking and Taste ID. If one has both, even regular foods like cooked fish steaks give stat bonuses, and magical foods get additional effects based on the Taste ID level. It would make cooking more valuable, and provide a reason for the Taste ID skill to exist.
Forensics is slightly more useful now thanks to the Honesty virtue, but perhaps there's more that can be done. Right now, using Forensics on a corpse gives some information about who has interacted with it. It also identifies corpses that can be made into trophies, and identifies thieves. This one's a toughie, but I'll welcome suggestions. One idea that comes to mind is the ability to set a bounty on a player up to a certain amount / time limit based upon skill level?
Begging's also tough, because of the negative connotation it has. I know there are occasional events where begging is used, but the ability to use begging to get lower prices at vendors may be a good place to start, or perhaps adding collectibles like books, etc would also add value to the skill. It already does come with a bit of Karma loss, as it should, I believe.