Cloud Based; Easily customisable without code; Apps for iPhone, Android, iPad; FileMaker Alternative; Free for Non-For-ProfitCons:
No Printing Templates; Filters can be limited depending on the fields.
One of my favourite must have tools. I've used it in many non-for-profit orgs as an alternative to disconnected and messy spreadsheets. I've seen it used in Film Festivals, Vounteer Rostering and Event Planning. It can also be an awesome Intranet alternative.