Groonga is a fast and accurate full text search engine based on an inverted index. Newly registered document instantly appears in search results, and updates are allowed without read locks. These characteristics result in superior performance for real-time applications. It is also a column-oriented database management system (DBMS). Compared with well-known row-oriented systems, such as MySQL and PostgreSQL, column-oriented systems are more suited for aggregate queries.
With a small codebase, the PowerDNS Recursor is an advanced resolver currently serving the DNS resolving needs of over 80 million Internet connections. Besides high performance (using kqueue or epoll, over 100 thousand qps on commodity hardware), it provides advanced anti-spoofing measures. In addition, the program caches server performance and timeouts, making it both network and user friendly. It also has built-in hooks for making graphs with rrdtool, providing insight into nameserver performance.
Xpdf is a viewer for Portable Document Format (PDF) files. (These are also sometimes also called 'Acrobat' files, from the name of Adobe's PDF software.) The Xpdf project also includes a PDF text extractor, PDF-to-PostScript converter, and various other utilities. It runs under the X Window System on UNIX, VMS, and OS/2. The non-X components (pdftops, pdftotext, etc.) also run on Win32 systems, and should run on pretty much any system with a decent C++ compiler. Xpdf is designed to be small and efficient. It can use Type 1 and TrueType fonts.
Converseen is an image converter and resizer written in C++ with the powerful Qt4 libraries. Thanks to the Magick++ image libraries, it supports more than 100 image formats like DPX, EXR, GIF, JPEG, JPEG-2000, PhotoCD, PNG, Postscript, SVG, TIFF, and many others. Converseen allows you to convert, resize, rotate, and automatically flip an unlimited number of images. It can save you time because it can process more than one image with one mouse click. It features a very simple user interface without strange options.