visiting cards... what do we do with them?

do we store visiting cards? or throw them?
we start with storing, and periodically spring clean them to throw out old, outdated ones...or so i thought... and rightly i think...since that tiny bit of paper contains a mine of information (again, this is what i think)... being in the trade that has largely to do with people, journos often face this issue of contacts... the next story's contacts are contained in that tiny info-pack...
so i got wild yesterday when at a conference, a lady, representing the company that held the event, comes forward and introduces herself and we exchange cards...
the conference begins, the Q&A happen and as we disburse, the lady gets up from the chair next to mine and drops all the cards that she has collected, including mine...
like umpteen times, i thought it was oversight and so i bent down my frail (!!) self, picked all the cards and ran behind her to give it to the lady...
she was busy with someone else, talking and exchanging cards... so when i butted in, handed over the cards to her and said, "you dropped these," she says, "oh how sweet, but i don't think i will need them."
i was beside myself by then... so to avoid an altercation, i walked out, making loud pit-pat with my shoes, as if the smooth granite beneath my feet was at fault...