15 also seems to be a somewhat significant number in my dreams. (The ones that don't involve any calculations in an attempt to get to 15 are bolded)
Unknown date after February 16, 2006 (Illusen from Neopets was in the dream, so it has to have been after I joined Neopets) and before August 19, 2007 (since I don't think I was on LJ at the time) - I had a dream that Wikipedia could automatically write a 30-, 60-, or 90-page essay about any article for you. All of these numbers are multiples of 15.
January 24, 2010 - Haley Prophet gave me a choice of FIVE things to do, and the fourth was to watch her compete in a horse race with FIVE participants where each participant had to bring FIVE rings that eventually turned into fruits to their starting position. Three fives add to 15. (There was another five in the dream - I went from a room where it was 1 PM to where it was 6 PM, a difference of five hours - but if you only count the obvious fives in the dream, there were three of them.)
July ?, 2010 - Remember the dream from the other post where the 651 on a road sign changed to 666? That's a difference of 15.
July 5, 2010 - Fifteen bikinis
August 6, 2010 - I dreamed that I was banned from LJ for 90 days. 90=15×6.
August 12, 2010 - The Super Mario World-styled timer I thought of started at 15
September 28, 2010 - The score between 16660 and 16669 could have been 16665, which would be 15×1111. (I'm wanting to think it was 16669, though.)
October 2, 2010 - 666-606=60=15×4.
On September 27, 2010 I had a dream that my alarm clock said it was 5:192 AM. Normally whenever I have an irregular time dream like that, I'm always scared of what'll happen when it reaches 5:200 or whatever and feel like I need to have it fixed somehow; however, this time, I was only mildly startled and then just stared at it, apparently knowing that it was a dream. Wonder if it means anything?
On October 1, 2010 I went to bed after I got home from school and had a dream that I was trying to explain something to my English teacher, but no matter how polite the words I said were, I always ended up unintentionally saying them in a rude way. Eventually, to get away from accidentally saying anything else in a rude way, I left and went into this weird bathroom where at first, everyone else in there somehow appeared as Yoshis (and only green Yoshis; apparently, Yoshis are racist now) even though I somehow knew they weren't. After a while, they changed to Luigis, and then the bathroom was somehow now on its own cubic planetoid with a cube of mirrors for a sky. Both the planetoid and its sky would turn themselves inside out every now and then. And not just the way you normally turn a cube inside-out (i.e. unfold it into a cross and put it back together the opposite way); one side might also go straight through the opposite side. (If you're interested in the fourth dimension, think of a four-dimensional cube rotating. It's like that except it didn't go into the fourth dimension.) Apparently, the planetoid (and maybe the sky too) also changed from cube-shaped to sphere-shaped later. At this point, the everyone-except-me-appearing-as-Yoshi-or-L