We've launched a beta version of our construction management software and have demoed it to a a few people within the industry. Everyone's initial reaction is "this is really cool", but they don't actually register and give it a chance.
What's the best way to attract users and get them more interested to sign up?
If they are looking at your website but not signing up, then I would look for problems with your website. It may not have a clear conversion channel, or may not instill enough confidence in the visitors.
If you are actually speaking with them in person, and they think its cool but don't sign up. Are you sure you have articulated the value to them? There is a difference between cool and seeing the value and wanting to use it.
You haven't provided a lot of information, so it is hard to offer more ideas. I guess your best option is to ask them? No harm in calling and saying "hey, we did a demo and you seemed to like it, but you haven't signed up. Would you mind providing any feedback why so that we can improve our offering".
What is the point of registering? If you want people to give your product a chance, then just let them give it a chance. It seems like you crossed an incredible milestone of getting users to even visit your site. This is HUGE. Take advantage of this and don't let them leave without trying your product.
This IMO, can be accomplished in several ways:
Check this post out on how to create a million dollar business: http://www.fourhourworkweek.com/blog/2011/09/24/how-to-create-a-million-dollar-business-this-weekend-examples-appsumo-mint-chihuahuas/ There's some great insight in there, such as how to test with Google Adwords to see just how interested people are. You can target in certain keywords and give a brief outline of what you're offering and put in an opt-in form. If people want to hear more, they can opt-in.
If the initial interest is there, then you can considering a free trial. Then it's a matter of continually asking questions and refining your product to meet your ideal customer's needs.