When presenting at a conference like SXSW, make business cards with your session info on them, including the session title or topic, location, and time. That will help promote your session. Also, your card will serve as a reminder of what you spoke about so that when people return home, days or weeks go by, and they finally look through the dozen or more cards they collected, they’ll remember who you were and why they wanted your card. Try to leave white space on the card too so you or the people you give the card to can write notes. Lastly, this session info serves as a credibility indicator. It shows that you presented at a major conference. You can even keep handing out the cards for a period after the conference, since A. you’ll have plenty of cards left over and it’s dumb to waste them, and B. why not tastefully brag a little? Let the world know you’re awesome, but without having to say it out loud.