Whoops! I meant to add a few online businesses I use as well. Here goes:

If you’re also an online business (as in you do sales online, but really, even if you don’t), you have got to get using some of the great SEO tools out there. Maybe this falls in the ‘obvious’ category you mention, but the tools we use include SEOmoz, Yahoo site explorer, Google webmaster tools, Google Website Optimizer, and really, there are a few other great ones there, but that’s what comes to mind right now.

This next one isn’t a tool itself, but if you check out AppSumo, they regularly bundle a bunch of web apps into an amazing deal – we bought a few of their deals, which included great deals on apps such as FreshBooks, MailChimp and CrazyEgg, to name a few.

Also, I really agree on the HubSpot comment – they do have an amazing array of great free resources and I attend their webinars regularly.

Thanks again!