| Fingerboard Markings
I just started studying with Glen Moore and one of the first things he did during my first lesson was get out a white ink (water soluble) pen and put marks on the side of my fingerboard on the first three stops, and the locations of the nodes for 1/3, 1/2, 2/3 and 3/4 string lengths in the middle of the fingerboard. This wasn't so much about intonation for closed notes, but as a guide for finding harmonics in the upper partials of each string. Then we worked on chromatics and finding various harmonics at or near every stop. For that purpose, markings were very helpful. I went to an Opera Theatre gig that evening and the first three dots screwed me up so much because I paid too much attention to them, I scraped off all of the lowest ones.
The next lesson, I asked him about intonation in general, and specifically about markers. He mentioned that Edgar Meyer has them as an example of how it seems unlikely that they'd undermine your playing, but also promoted constantly checking your intonation during practice so on the gig solid intonation is more natural and something you can automatically get to, while saving more concentration for execution or expression. In effect he supporting the thought that good intonation is a life-long endeavor and any player should use any method or device that works for that player.
While I don't really like having markings and feel like they tend to hinder more than help, I also do check my position relative to a little knot in the side of the neck of my bass that I know is relative to where my thumb should generally be in 2nd position. If I can't hear a pitch in the mix very well, I'll glance up. If I have to nail a D above the octave G on the G string, I'll put a little mark there without hesitation if it helps me nail that note cold.
I also agree that markers won't help much if you're not listening to yourself and the people you're playing with. Intonation is not a fixed quantity. It will change with those around you and the place your note has in the harmonic structure. In an orchestral section, if I play a low G and somehow know that it would yield a 'perfect' reading on a tuner but it sounds flat compared to the section, I'll adjust. I often do, as a matter of fact, even if I think the section isn't 'correct.' It'll be much easier for the rest of the orchestrat to tune to three basses playing the same pitch that to give the high strings three options to tune to on the bottom.
Good, Bad or Ugly, whatever serves to help me play with better intonation and be a more effective bass player is what I'll strive for.
Tanglehead | 
Don't EVER try this at home.
