Wow! I really like everything you guys have posted so far. Funny that everyone posting has had some substantial work done.
I'm in the middle of getting a half sleeve done on my left arm and here's where I'm at. I actually go back this Saturday for another session. I'm more into abstract designs than the tradition tattoos and I was told to reference work done by a guy named Mankan who's based somewhere in Europe. I took some printouts to Dave at Atom Bomb (just east of Cleveland) and I'm extremely happy with the custom piece he's coming up with for me (in fact, I wouldn't let anyone else ink me after having such a good experience with him and his shop). I guess it's called "negative space" and what appeals to me about it is that it will have a layered or 3D kind of effect due to the shading and deep blacks.
I have another one on my back, but no picture handy. I attached the picture I based (copied) it off of. I originally wanted the whole design on my back but when I went to get it done (I was 18 and this was about 9 years ago) the artist made it seem like it couldn't be done without taking up my whole back and costing thousands of dollars. I ended up getting the middle part (basically what's in the white box) done and it's about the size of a piece of paper. Looking back I think a better artist could have done the whole thing but I am still happy with how it turned out (black and grey of course).
What's funny is that the half sleeve I'm getting was originally intended to cover up a small one I have on my right upper arm (I hate it so much I won't describe it) but I liked the concept enough that I didn't want him to have to compromise and I'm putting the cover up off until it's done. So as soon as the sleeve is complete in a couple months I'll be going right back in for work on my right arm.