As a Mac ISV, I'm fairly isolated here in The Woodlands, Texas. That's why I love it when I get a chance to get out and meet with other developers and small business owners to discuss ideas and sharpen my skills.
Last year was my first time to attend Apple's WWDC and it won't be my last. There was plenty of learning to be had from the speakers at the conference but I gained just as much knowledge, if not more, from other developers who I met there. The fellowship was worth the price of attendance alone and the connections I made are still reaping rewards.
One conference that I'd love to go to but just don't have the time and budget for right now is the NSConference run by Steve "Scotty" Scott of The Mac Developer Network fame.
The speaker list is great and there are so many developers that are going to be there that I'd love to hang with. Unfortunately, I don't think I could sneak away to Europe again without taking my wife (I've been there several times and she hasn't at all). I think my daughter would have a throw down fit too so the budget wouldn't be just the inexpensive conference and lodging costs plus a bit of airfare but instead, it would turn into a family vacation with all the requisite tourist activities—more than I care to spend right now.
But if you are in Europe or can invest a little time and money on travel, plan on attending this conference. Then you can come back and leave comments here about all the cool stuff I missed and make me very, very jealous.