Nothing crazy valuable. Off the top of my head the best thing you can steal is All-Divides from Mimics. There are only so many mimics from the game, but if you steal from it and run you can repeat the process. I always save that Mimic in the Fire Temple for later when I have the Colette's stealing skill, then I go back and start farming only to realize I never use All-Divides anyway.
There are also Rune Bottles and herbs that are stealable but I think most/all of them can be obtained as drops, probably more easily.
There are also Rune Bottles and herbs that are stealable but I think most/all of them can be obtained as drops, probably more easily.