I've played around with a few various web app solutions for small businesses. The last ones were the Sugar CRM, and Microsoft. However, I've decided that Google Apps for Business is the way to go. Here's why:
* I love the email SPAM filtering Google provides more than anything else I've tried.
* The build-in Google Drive (formerly docs) is by far my favorite online storage and document editor
* There are integration modules for Google Drive for my Drupal installation
* I already extensively use the Google Calendar
* It seamlessly works with my smart phone
* Google remains one of the very few technology companies that still has my respect
Additionally, I'm working on a web site repair where a Drupal site has a very large number of PDF's and raw HTML files that are uploaded, but need to be visible only to authenticated users. This is one step closer towards keeping the simple method of mass uploads, but using a module to manage permissions and view-ability. Also, Google calendar is pretty easy to integrate into web sites.