I've been to assorted conferences. The one I reguarly attend is the lib@cam conference, which is an annual event. I do listen carefully to the lectures and presentations, but it gives me an excellent chance to catch up with ex-colleagues, friends and fellow (and now ex-) Aberystwyth students. The last one I went to led to me being taught how to catalogue periodicals.
The most successful talks are from people who make me think, both about my current job, and what the profession will be like in the future. The least successful are from businesses who try and sell their product, having not realised they'll be talking to a range of professionals, not just the head honchos with the buying power.
I'm unlikely to organise one, or even speak at one, but I'm always happy
to go to them, provided someone is on hand with a tea urn. And a
biscuit. At present, the only topic I'd be good at presenting would be book covering - I've been doing that for ten years, have demonstrated it to numerous librarians and interested students - if only to show that sticky backed plastic can't bite!