I've used SOBI2 before for the basic business indexing purpose it was built for, and it works great out of the box. There are plenty of settings to tweak and adjust to get your site running exactly how you need.

What really impressed me, though, is my experience with the newest site I've put together. There were two basic components that I needed for the core functionality of the site: a file listing and a basic store.
I found that DOCman and reMOSitory didn't offer some features I would need for this specific file listing, and the different shopping cart solutions such as VirtueMart and ECJC were overkill in some areas and lacking in others.
Without too much trouble, I was able to modify SOBI2 to meet my needs for both tasks. I'm now running two separate modified SOBI2 components on my site, and it's working perfectly.

I would recommend SOBI2 to anyone needing any sort of directory on their site. If you're just a little creative, you'll be able to adjust settings or modify the code to suit your needs.