Here are a few every-day useful apps I have picked up over the years:
Carries out all the maintenance tasks you could want for your mac simply and easily; including virus scanning.
Cloudmark DesktopOne http://www.cloudmark.com/en/products/cloudmark-desktopone/index
Intelligent spam protection tool for your email that uses several techniques including blocking emails that other users of the program have blocked. Works with Mail app and
A simple tool that lets you allow or block incoming/outgoing internet communications from your applications separately for greater security.