I like Fridays, as I think most people who work a regular work week or go to school do, so I think its funny that it would be a Friday that would get branded as the unluckiest of days. Of course, the most commonly cited origins of the superstition go back long before the formalization of the modern work week (Roman times?). There are various places you can read about the origins and myths surrounding Friday the 13th (most commonly cited: the Bible, The Knights Templar, negative associations with women and the lunar calendar etc). I thought www.crystalinks.com/friday13th.html offered a nice summary (with pictures!).
I also learned that Friday is traditionally not a good day to start projects. I particularly liked the needlework quote below posted on http://www.snopes.com/luck/friday13.asp
"I knew an old lady who, if she had nearly completed a piece of needlework on a Thursday, would put it aside unfinished, and set a few stitches in her next undertaking, that she might not be obliged either to begin the new task on Friday or to remain idle for a day." (1883)
No one mentioned however, that in Mexico (and perhaps elsewhere?) Friday the 13th is a lucky day. This may be because of the number 13 special significance in the Mayan Calendar. (And you can begin to read about that here: http://www.caribemexicano.com/eng/mayancalendar/)
So what’s it been for me, definitely lucky! I received an unexpected raise, and Jorge had an unexpected sale. May the stars so favor you as well!