People are often livetweeting from a mobile device, so bonus points if it’s an easy-to-remember short url (you can make custom ones at bitly.com and other places). For example, rather than bit.ly/aSdfvoPaZWQ which is hard to tweet especially if it’s only on one slide for a few seconds, you could make bit.ly/SmithNWAV43 or bit.ly/wordsfromyourtitle and then put it in the header or footer of all your slides or at the top of your handout (if it's only on one slide, it may pass by too quickly for someone to type into a tweet). 

You don’t have to be any good at tech or have a website or webhosting in order to make a sharable handout these days: you can just put a pdf on Google Docs or Dropbox and get a sharable link which you then shorten so people can remember it. In fact, if you have a professional twitter account, you can even tweet out a link to your own handout in the conference hashtag sometime before your talk (with the time/session info), so people who are looking for you can find you even more easily!

Other reasons why having your handout or slides online in advance is a good idea:

1. If you didn’t make enough copies, people with a computer or tablet can follow along there instead. 

2. If anyone in the audience is visually impaired, an electronic version allows them to zoom in and/or use a screenreader. 

3. You won’t forget to put them online after. 

4. People who like your talk and want to mention it to someone (who perhaps works on a related topic) have a url that they can email to that person immediately, rather than trying to remember to pass on a paper copy. 

5. Of course, an online handout is great for people who miss your talk, because they’re in a parallel session or they can’t make it at all but are following the livetweeting.

If you have a professional twitter account, it's also a great idea to put your twitter handle on your slides or handout, so livetweeters can properly attribute your talk. If not, at least put your name on every slide so that we can spell it correctly. (This goes for questions in the Q&A as well -- if you want your question attributed, say your name before asking. And do it even if you're a big name in the field, as livetweeters may not be in your subfield or may be grad students attending their first big conference.) If you'd rather not have people livetweet your talk at all, you can also feel free to say this before your talk. 

Conference organizers: it’s also useful if you can tweet a link to the conference schedule, program, abstracts, etc, especially at the beginning of the conference so we know which hashtag to use.