Ah, yes, your first kiss from sweet lady chemistry. She can be a real ***** at times. Nitric acid yellows skin on contact, it's just the way it interacts with skin proteins.
It seems like you've had a mild exposure, I had one of those once: I was using nitrile gloves one size too small, and was working with con. nitric. I felt the moisture on my middle fingertip, and I knew the cause -- if gloves are too tight, they become more permeable, even if they don't rip. The group didn't want to take any chances, and made me rinse in cold tap, and soak in bicarbonate solution. It was a tiny exposure really, but I got the skin yellowing you got. In time, the yellow spot will dry, and peel off.
Concentrated HCl just makes the skin red, a typical chemical burn. I've never had a conc H2SO4 burn, I do know it chars paper rapidly, but I don't know what it'll do to skin.
Aqua Regia, as they told me, will simply rapidly strip your skin clean off. Hence, my "belt and suspenders" mode in the photo here:
http://www.chemicalforums.com/index.php?topic=23722.msg90280#msg90280