I guess you can trace my interest in these type of pictures back to freshman year at UC Davis when I happened upon a dude selling posters in front of the Coffee House early one day Fall quarter 1987. I ended up purchasing my first Salvador Dali print. 
At the time I fancied myself an open-minded adventurer who was eager to push the envelope and explore the infinite possibilities of normal human perception by any and all available means. In other words, I was eighteen years old and away from home for the first time in my life. I proudly decorated my dorm room with that poster — among others which included Jessica Rabbitt and Brian Bosworth. It was the eighties and I had horrible taste, so sue me.
A few months later a friend of mine turned me on the works of MC Escher. I couldn’t believe what I was supposed to be seeing. Hours seemed to tick on by as my mind struggled mightily with what my eyes were telling it they saw. Throwing more fuel on the fire in my brain was my collection of Where’s Waldo books and their innate ability to occupy chunks of my precious time. (I would venture to guess that that was probably the first time that Escher has been mentioned in the same paragraph as Waldo).
Spring quarter later that school year brought with it my first ever Whole Earth Festival on campus. The three day celebration of Mother Earth, natural foods, hippie music, Birkenstocks, patchouli oil, and sweat was so much fun for me and my friends that I almost dropped out of school so that I could follow the Grateful Dead around on tour. No, not really, but I did buy this super-groovy tie-dyed t-shirt that had what looked like a skull on it but upon closer inspection was actually a drawing of a woman looking at her reflection in the mirror. The picture is called Vanity and it’s posted above. Pretty crazy, eh? (The Canadian in me couldn’t resist not saying eh).
Fast-forward to the current year of (practice with me) twenty ten and I discovered these three pieces of eyeball ingested brain candy while checking my mail on Yahoo. I decided to post a few of my favorite illusions here for you to trip out on. Enjoy.
Which arrows do you see first? The yellow ones or the green ones?
You realize that the fishies aren't moving, right?
Ahhh! The blue dots! Make them stop!
The Adventures of ALS Boy 
Totally groovy… Love the psychedelics!
I kept a Dali calendar in my dorm room every year (partially because I love his work, and partially because it greatly disturbed my roommates!) — and I share a birthday with MC Escher!
The arrow illusion reminds me of your (fairly) recent FedEx revelation.
You forgot to mention the “3-D” Magic Eye craze that swept suburban mall kiosks in the early 1990s. I could only see those darn things about 15% of the time — guess my eyes just like to stay in focus!
traci, i was like that guy in the movie mallrats who never saw the stupid boat
LOL, Jas. I’m with ya!
I have that Dali framed and hanging in my office. It’s called “Hallucinogenic Toreador”. I think it is my favorite work of art.
Doss and I were looking at it a while back and realized for the first time there is another toreador hidden in the painting (not the little guy at the bottom). We couldn’t believe after all the time we spent staring at that painting that we never saw it before.
Dali was quite a trip!