Business's in general, should be thinking about are the following items.
An ERP solution: There are numerous components from which to choose, including Openbravo or Compiere (for ERP), MySQL or EnterpriseDB (for databases) and Linux (or Windows Server).
A CRM solution: Leverage options like SugarCRM or Concursive, plus a database and Linux or Windows Server.
A point-of-sale solution: Leverage open source solutions like Openbravo POS.
A collaborative software solution: A lot of companies — large and small — are embracing Zimbra email, and there’s plenty of buzz around Open Xchange.
VoIP and Unified Communications: Asterisk, the open source PBX. Digium leads that market, but there are plenty of other companies to check out. Fonality, for one, has attracted Dell’s attention. Oh, and The VAR Guy wrote a bit about Voiceroute, a unified communications specialist, earlier this month.