11) Vicidial: Asterisk is very powerful and makes for a strong PBX product, but there are some fantastic add-ons that can make it even better. Vicidial is one such example. Designed to make predictive calling affordable, Vicidial is nice because it fits nicely into the existing communication structure, rather than trying to layer together a few different expensive proprietary products.
12) Openproj: There are always a variety of open source options for virtually any enterprise application you can think of. Project management software is certainly no exception to this rule. Openproj is one such solution and, despite its recent acquisition from Serena Software, it's said that Openproj will continue to be made available to all who are looking for a strong project management suite.
13) Openmeetings: It seems that acquisitions are in the air right now, with another open source meeting solutions being bought up by Salesforce. Luckily, Openmeetings is still free from this trend and, unlike DimDim, it's not tossing their users out like yesterday's newspaper.
What makes using Openmeetings so exciting is its embrace of other open source solutions like Moodle and SugarCRM. This means that conducting meetings that involve contact info or scheduling can be done easily, thanks to some forward thinking from the developers.
14) MediaWiki: If you're looking to run a wiki for your company and would like to use the same kind of functionality found with the Wikipedia project, then I 'd suggest you take a hard look at MediaWiki. Known to be the nuts and bolts behind the super-successful portal Wikipedia, MediaWiki is easily among the best of the open source Wiki solutions available today.
15) LimeSurvey: Simple, yet very powerful and effective is how I would describe the open source LimeSurvey software. It makes creating an open source enabled online survey relatively simple. Rather than fighting with ad-filled, sloppy alternatives, LimeSurvey ensures you're not potentially infecting your customers with questionable code or malware of some sort.
16) OpenBravo: Said to be among one of the best ERP (enterprise resource planning) software suites available, OpenBravo allows you to dedicate your funding to other mission critical projects and leave the ERP stuff to this solid open source option. This software suite comes complete with built in Integrated Accounting, Sales & CRM, Procurement, Inventory, Production, and Project & Service Management solutions.
17) Ekiga: Skype for SIP fans is how I've heard Ekiga described by some of its fanbase in recent years. Definitely the strongest Skype alternative I've ever used, I also love the fact that it works extremely well when used over a LAN. So you can communicate with others in the office, in addition to using its Skype-like functionality.
18) Dolphin Smart Community Builder: Rather than placing the your social networking needs into the whims of Facebook or Twitter exclusively, consider adding Dolphin Smart Community Builder to your social media strategy. The software is perfect for creating and managing dating sites, social networking portals and other similar niche communities where your company is in complete control from Day One. This is much more than a mere social media tool its a full-on community building software.
19) Compiere Community Edition: Because it never hurts to include more than one ERP suite in a list like this, Compiere Community Edition is a good alternative for any company not interested in using OpenBravo. Despite the push for buying the paid edition(s) of the software, Compiere's community edition does provide quite a bit of ERP functionality that users need within the enterprise realm.
20) Otrs: Like most concepts in the open source help desk area, it's safe to say there is never a silver bullet here. But for what it's worth, I think that Otrs is pretty darned close to being perfect for the needs of most companies. What makes using Otrs so powerful is that this is much more than mere help desk software. It also provides for sales/pre-sales support, billing and internal IT support as well.