This conference has a HUGE expo floor and is quite affordable to startups. I think the New York event tends to be much better than the San Francisco one, because I get to see tons of companies I've never heard of. There are also a lot of media people and more cross-industry networking.
Due to the location (an enormous warehouse on the water) it is always freezing cold.
Awesome hackathon. You can participate and get in free.
An extremely well produced event, certainly one of the best in Europe. If you're in the U.S. and have been meaning to visit London, June is a lovely time to go drum up some new business and see the sights.
Startup Weekend is a great event for evangelizing your product if it can help people to launch their startups over the weekend. I also think doing Startup Weekend together is a great pressure cooker for your team to bond in, or even find new people to work with.
It's generally frowned upon to come with an already formed startup team, so be flexible and prepared to work on a project for the weekend as an exercise - you don't have to take it further. But who knows what you might find.
BarCamp takes place in cities around the world. It isn't an appropriate place to promote your company, but it is an extension of the digital community and you're likely to find kindred spirits and potential employees and cofounders at these events. Definitely a community worth being a part of.
South by Southwest is many things to many people. Real deals do get done at this show, but in recent years it has become a branding battleground for emerging companies. It is also well known for epic parties battling to be the best every night.
Last year's even was drenched in torrential rain nearly the entire time, but usually Austin in the Spring is a warm reprieve from less temperate climes around the U.S.
Startups can simply send a team member or two for a few days to network, or band together to host a party. I don't recommend the show floor or startup accelerator events - they don't bring in the best traffic. The most successful companies find a guerilla marketing gimmick that ties in with the show attendees in a quirky way.
Gigaom's Structure conference is all about cloud technology, and is run as a single track event with a small show floor that is primarily dominated by larger enterprise players. If you are competing in the cloud storage, developer tools, or infrastructure-as-a-service sectors you might want to have a presence here. Simply attending for a day, or hanging out downstairs in the cafe for free, offer great networking opportunities for cash-strapped companies.
Longest running monthly event showcasing new startups in the Bay Area. I think it is not as popular with the cool kids, but I love it because it showcases very early stage companies I've never heard of. Feels like a rite of passage.
I think Robert Scoble puts it quite well: "Dent is one of my 'must-attend' conferences. It promises to be another one of those events everyone is talking about and nobody can get in to." I've never been.