Where I'm from 11:11 is considered good luck. You're supposed to "make a wish" when it's 11:11, kiss your finger and touch the clock.
The reason you "see" these times all the time is psychology... they stand out to you because they "mean" something or have an interesting "look" to them.
Relating this to advertising (our world) we see literally thousands of ads each day. We only remember a select few. Why do we remember these ads that stand out? Mostly because we have a reason to... we like the company or the ad, we are familiar with them already, we've seen it everywhere. It's our job to build this "brand".
4:23 is a "brand" to you. So is 11:11 because it's the only time that has 4 of the same number (unless you go by military time 22:22). Regardless, I guess the pinnacle of a brand is when your company name becomes synonomous with the industry (Xerox, Coke, Google, iPod, Kleenex)
Wow... this may be in my Top 5 most bizarre posts ever.