Most guitars you've seen have dots as position markers along the fret board. It's not the most obvious place for a musician or guitar owner to express themselves, but it's one of the places that has some of the best artwork available.
Perhaps you've seen the guitars that have "shark tooth" inlays or perhaps even something more outlandish. The following are some of my favorites and range from mild variation of dot markers to outright garish.
This eclipse inlay is probably the one I would have if I could afford a custom-built guitar. It's simple, uncluttered but still neat. I really like it.
My next favorite is this double helix. However, without good side position markers, I'm sure I would get lost on the fret board. Cool looking though, huh?
I adore this inlay. I can't imagine how long this must have taken. It's gorgeous (and I love tigers). There's no way I could play this. This would the kind of guitar I would buy to display. And believe me, if I had that kind of money, that's exactly the kind of thing I would be doing.
Lastly ... well, there's a point where there's just too much. In my opinion these guys crossed it a while ago. However, this is a very popular, well, common anyway, design on JET guitars. It's a jungle scene with parrots, if you can't make it out.
All these images are from Ed Roman Guitars. His inlay gallery has some great examples of what's available out there.
Part 21.4: A shout out;
Part 21: Cop Out;
Part 20: Lenny Kravitz;
Part 19: Is it guitar or is it Korg?;
Part 18: A beautiful guitar;
Part 17: Getting all amped up over the sound;
Part 16: Not quite plug and play;
Part 15.25: Don't let Gibson buy your company;
Part 15: The greatest guitarist you've never heard of;
Part 14: The finish;
Part 13: Vernon Reid;
Part 12: The vibrato tremolo;
Part 11: Jimmy Page;
Part 10: What's in the wood?;
Part 9: Rebuilding a guitar;
Part 8: G3 2005;
Part 7: John Petrucci;
Part 6: Chingon;
Part 5: Home recording on the cheapity cheap;
Part 4.01: Guitar Zen;
Part 4: Full service Friday -- concert going in 1993;
Part 3.5: Gretsch guitars;
Part 3: The Reverend Horton Heat;
Part 2: Back when I thought I could play;
Part 1: Zakk Wylde then and now