awesome applications you've never heard of & operating systems you've never heard of

 Minix
Small Unix variant and a learning tool

Minix is famous within the alternative OS world for two reasons. First, it was the platform on which Linus Torvalds developed the first version of Linux; and secondly, its code is covered extensively in Operating Systems: Design and Implementation, a book written by the Minix author.

Visopsys
Small OS focused on disk partitioning

All of the projects covered so far have been the work of many people. Visopsys, however, is particularly striking because it's almost entirely the work of one developer, Andy McLaughlin.

Since he wrote the first lines of code in 1997, McLaughlin has focused on "cherry-picking the best ideas from other operating systems" and produced a compact OS with powerful partition management tools. It even has some spin-off software.

FreeDOS
Maximum compatibility with DOS software

While ReactOS's ambitions are seriously lofty, FreeDOS has a considerably simpler job: running DOS programs. That still involves plenty of work, of course, but DOS has essentially been fixed in place for the last decade, so there aren't new APIs to chase around and implement.

Two CD ISOs are available: Fdbasecd, a small 8MB base system with limited functionality; and Fdfullcd, a 153MB beast packed with software and drivers.

Plan 9
Research beyond Unix

Plan 9 aimed to expand beyond the Unix philosophy of representing almost everything as a file: in Plan 9, even network connections and the user interface can be manipulated via the filesystem. Additionally, a communication protocol named 9P was developed to allow Plan 9 machines to share resources.

Ultimately, Plan 9 hasn't achieved anywhere near the same level of success as Unix. However, it's still undergoing development and is a source of new ideas for OS programmers.

 KolibriOS
 Extreme performance and compact code size

Without a doubt, KolibriOS wins the award for the most ambitious project in this feature. It's a fully fledged OS written entirely in assembly language. The KolibriOS team has managed to squeeze pre-emptive multitasking, a graphical desktop, TCP/IP networking, USB support, media playback and many other features onto a 1.44MB floppy disk.

Booting 'kolibri.img' brings you to the desktop in just a couple of seconds. There's a Windows-like Start menu and taskbar along the bottom of the screen, and the desktop is littered with small utilities.

Unlocker

Bypass common Windows errors

If you’ve used Windows for any extended period of time, you’ve been slapped in the face with various errors. Some of the most common include those claiming that folders or files cannot be accessed or deleted because they’re being used by another user or program.

I’m sure you’re tired of combing through your drive with a magnifying glass trying to isolate the conflict. Unlocker is a small utility which provides a solution to that common headache. You can simply right-click the troublesome file or folder and call upon the aid of Unlocker. When the program opens, it will provide a somewhat detailed list of “lockers.” It offers the ability to end an individual process as well as unlock both a specific target and all found targets.

Unfortunately, at the time of writing Unlocker (v1.8.7) is not yet compatible with 64-bit operating systems, but the developer is working on it. If that’s a bit of a letdown, pick your head up and check out LockHunter instead.

DVD Flick

Transform your video files into playable DVDs

This program succeeds in its attempt to provide simple, yet powerful, DVD creation. DVD Flick converts and burns virtually any video file to a DVD that will work in your home entertainment center’s DVD player. Impressively, it supports over 45 popular file formats, 60-plus video codecs and more than 40 audio codecs. You can easily combine multiple files, add your own menu, subtitles and audio tracks.

The user interface is very straightforward and intuitive, especially for a tool in this category. To get rolling, you can literally just specify a source file, and click “Create DVD.” Among the supported file types are AVI, MPG, MOV, WMV, ASF, FLV, MKV, MP4. Codec support includes MPEG-1/2/4, Windows Media Audio/Video, MP3, OGG Vorbis, H264 and On2 VP5/6. Given its wide-spectrum functionality, I can nearly promise you that you’ll be able to transform nearly any video file into a fully working DVD.

Dropbox

Sync data seamlessly across all your PCs

The importance of having a PC on the run is made evident by the sheer scale of today’s portable computing market. From smartphones and PDAs to netbooks and notebooks. With multiple sessions logged across various devices, coordinating data between them can be bothersome to say the least. If that sounds like you to any degree, Dropbox might just be what you need.

1. 

Dropbox is an easy-to-use cross-platform utility which runs silently in the background of your system. The program creates a dedicated folder on your system, which you can interact with in the usual manner. By placing a file within your Dropbox folder, it is automatically synced over the Internet to other designated computers running the software. Data is displayed with a checkmark and arrows to indicate synchronization status.