Your company\u2014or your users\u2014have decided that at least one department's computing needs are best met with shiny new Macs. Or perhaps you've seen the financial benefits of adopting Apple products. Now, what applications are you going to put on them? There are loads of options that are tailor-made for the enterprise, but seven open-source solutions really stand out from the pack as must-haves for the Mac users in your workplace.Need advice about choosing enterprise-ready open-source solutions? Our experts shared tips on evaluating business open-source applications. Also, see the results from CIO.com's own open-source survey, which showed that more than half of enterprises use open-source software today.1. Even the best-laid business plan can stall or die without attention to detail, but managing every nuance of a project is a lot of work. OpenProj is a robust project manager that's capable of producing charts, graphs and all kinds of reports to help keep your ship running smoothly. OpenProj handles budget data, time lines and Gantt charts, resource management, and it can compute a variety of different metrics. Though OpenProj is still a youngster in a market that's been dominated by Microsoft Project, according to the company's website, the software has been downloaded over 500,000 times since its launch less than a year ago.2. Moodle has long been heralded as a superior open-source course management system for educators, but it certainly has a place in the corporate environment as well. Because it was designed for online learning communities, Moodle is a perfect solution for managing your company training classes or professional development sessions.Moodle scales amazingly well. It handles classroom settings with 10,000 participants just as smoothly as it serves a small class of ten. Because it's open source, Moodle is completely customizable to a company's needs. Dozens of additional modules and plug-ins add extra functionality, such as podcasting and video conferencing. You may never be able to fully convince your staff that company in-services are fun, but Moodle can at least help you make it less of a chore.3. AbiWord is the often overlooked word processing app that's everything a company could want. AbiWord costs less than iWork for the Mac (it's free), it's easier to customize than the native text editor (it's open source), and it's less bloated than OpenOffice.org (AbiWord is 9MB versus OpenOffice.org's 158MB). Though it lacks the presentation and spreadsheets of a complete software suite, AbiWord is a robust word processor that's speedy and packed with useful features including spell check and advanced document layout options.4. Though Mac OS X ships with a native PDF viewer, it doesn't do much beyond letting you view a file's contents. Skim is both a top-notch PDF reader and markup tool designed just for the Mac. Use Skim to preview the internal links of a document, add notes, highlight text and more. You can even use Skim to create presentations and control them\u2014right inside the app\u2014using an Apple Remote. As more corporate documents are transmitted every day as PDF documents, this is one app you can't do without.5. The days of punch cards and time clocks are over, but the need to track employees' work hours isn't. Rachota is a small, portable application that runs anywhere and tracks multiple projects at once. Data is neatly displayed in diagram form and can be aggregated into customized reports for in-depth analysis. Rachota can review data and make suggestions on how to maximize or improve a user's time. Rachota supports 11 languages and is small enough to carry around on a thumb drive. Be forewarned, though: To discourage "creative" time tracking, this app was designed with limited manual editing capability; once you've set the parameters, they are exceptionally difficult to change.6. Corporate life doesn't occur in a vacuum. Even if you telecommute or work in a satellite office, you need to keep in touch with your coworkers and employees. Zimbra Collaboration Suite (ZCS) Open Source Edition boasts a handy set of instant messaging, e-mail and calendaring apps to tie together your staff communications. It works with Microsoft Outlook and other PC and mobile solutions, and is also cross-platform\u2014a handy thing if you work in an office full of Mac, Windows and Linux computers. ZCS Open Source Edition also has shared address books, document sharing and mobile support. 7. MacLibre is more than just a single useful app; it's a bundle of open-source Mac OS X applications. It includes the biggies like Audacity audio editor, The Gimp image editor, Inkscape for graphics and Adium instant messaging client, plus some lesser-known apps like Desktop Manager and Colloquy IRC client, which are often overlooked. All told, there are more than twenty applications in five categories, making MacLibre a one-stop shop for top quality open-source software.