The best free software to get your start-up business going

Last week, I came across an article on Entrepreneur.com that had a great list of free and open source software I think will be particularly useful to small start-ups and expansion stage companies. Give these a try and see if you can cut out some of your costs; you have nothing to lose!
 Dropbox is great! It lets you store and share files online. You get 2GB of free space, but if you want more you can pay $20 to expand to 100GB. It is very simple and easy to use. You can sync files of any size or type online and across computers. I really like the feature that allows you to make changes to a file on your computer. It automatically syncs those changes to the one that’s saved on Dropbox. Evernote is a scrapbook/notebook that makes it very easy to remember things using your computer, phone and the web. You can type a text, clip a web page, snap a photo, take a screenshot – you can capture anything and organize it manually or let Evernote do it for you. Later, you can search for any of these, even printed or handwritten text inside your images! You can use it across all your gadgets, from your iPhone and Android to your desktop and tablets. Google Apps is great for collaboration and communication in a business. It includes the entire package of Gmail, Google Calendar, Google Sites (for creating websites and group wikis) and Google Docs (online documents, spreadsheets and presentations). The free version limits to 50 users, which is perfect for start-ups! You can also get Google Apps for Business, which costs $50 per user per year. It does not set a user maximum.  phpBMS is an open source Business Management Software (BMS) that lets you create sales orders, track clients and prospects, fulfill account receivable needs and also allows you to print detailed sales and purchasing reports. There are no subscriptions! Lemon POS is a Point of Sale (POS) software, which means that it records each sale as it occurs, keeping your inventory records up-to-date. You can run reports and analyze sales data, maintain sales history and improve pricing accuracy by integrating bar-code scanners. All of these help you make better decisions about ordering and merchandizing. SugarCRM is a Customer Relationship Management (CRM) software that lets you organize and share your customer information, improve customer and prospect tracking, build forecasts, and share reports. It helps you collaborate information across sales, marketing and support teams. Again, it is open source! OpenOffice is the free version of Microsoft office. It is available in many languages. The full-featured set of office applications is available to Mac users through NeoOffice. 
Do you know of any other open source software that can help small start-up companies?