Publishers, literary agents, editors, authors, and other industry insiders from around the globe attend the Frankfurt Book Fair to negotiate international rights, network, and drink a whole bunch of German beer. (If it sounds mega awesome, that's because it is.) Alas, I'm not cool enough to be invited and don't currently have the spare cash to fly to Germany for a week (because if I did, I'd have already gone for Oktoberfest), but I've heard enough good stories to know that it's a productive and entertaining meeting.
The fair is open to the general public on Saturday and Sunday, so if you happen to be in the area (or feel like booking a last-minute flight), you can visit exhibitions set up by publishers from dozens of countries and learn about The Next Big Thing(s) in Publishing. I imagine it's a time-consuming and expensive endeavour, dear readers and writers, and I'm frankly (ha! "frankly") not sure how much networking you'd be able to do, so I don't recommend you go unless your editor or agent has specifically asked you along (in which case you're already there). That said, you can always ask him/her if it might make sense for you to go next year.
Conferences in general, however, particularly those run in the good ol' U.S. of A. by your genre guild of choice (e.g. the RWA, the MWA) are great events for you to meet agents and other authors, network, discuss your works in progress, attend readings, and so on, and I absolutely encourage you to try to attend one or two of these per year if at all possible. Trade fairs, conferences, literary festivals, readings, seminars, &c can be of immense value to you, your work, and your career, and as long as you're not breaking the bank to attend them, it's a good idea to make it to those being held in and around your area. If you've got the money to travel a bit, (inter)national events are great, too.
For those of you who have attended trade conferences (or even—be still, mein Herz—Frankfurt): how was your experience? What did you like best/least? Would you recommend that/those conference(s) to others, and why?
To the commments!