While no follow definitely does give you "link juice" (wow, that term is the worst), links on Twitter definitely have SEO value.
Besides for conversation, the second reason people go to Twitter is for content discovery. You definitely have a huge potential for traffic, and from social media, this is the biggest immediately boost that Twitter gives you.
Other things:
1. Build your community and your brand presence.
2. Get your name in front of people's eyes who might not have seen you.
3. Loyal community members really help you in the bad times. If you've build an awesome community who's loyal to your brand and say, the economy dives and you sell a luxury product, you'll see people still buying and advocating your brand. Or say when something goes wrong, people care a lot. For instance, at SEOmoz, when our tools were having tons of issues in Sept of last year, our community stuck by us and even made us a get well Roger card.
4. Serve as an extension of customer service. Using Twitter as customer service can cut down on customer service costs - a tweet vs a phone call. And also be an early warning for issues and save you money say if someone spots a problem with your product and you can fix it before hundreds/thousands notice.
5. Okay, a lot of those weren't SEO, but there is evidence that Google definitely indexes Twitter and while Twitter's links may be no-follow, Google isn't stupid and if they see a lot of people pointing out the same link / having the same conversation on Twitter, they know it's hot. Social signals do count. We just don't know for how much / how long they affect the Algo since we don't know the Algo's exact formula.
