Free lightweight software for linux

Lightweight C++ is a programming language that looks like C++ (a lightweight C++ dialect) and is directly translated to readable C by the lwc preprocessor.
Its more "K&R" and, well, more lightweight. Important thing about lightweight C++ is that by studying the generated C code it is easy to understand how OOP features are implemented and what is the cost of everything.
Adding new features and extensions is also very easy (much easier than adding new C++ extensions to gcc at least), and this is one of lwc goals: To keep evolving.
Main features:
- function overloading,
- member functions,
- inheritance,
- virtual functions (polymorphism),
- multiple inheritance,
- virtual inheritance and pure virtual functions,
- constructors, destructors,
- new and delete,
- default function arguments,
- simple exceptions (no auto destruction of locals)
- and a mechanism of simplistic templates (implemented as high-level multi-line macros).
- operator overloading (works with ptrs when it can)
- +other
Enhancements:
- Changed the generated code for the gcc cleanup attribute so that if a constructor throws, the destructor is not invoked. As in the simple case where we dont have the cleanup attribute and like C++.

ltpanel is a lightweight window list for the X Window System, similar to GNOMEs window list applet.

It has been tested on IceWM and should work with any GNOME-compliant window manager. It is based on Peter Zeleznys fspanel.

Koinpurse is a lightweight PHP+MySQL application for keeping track of shared bills, such as utilities in an apartment or townhouse.
Main features:
- PayPal integration
- QIF export

steelme is an open-source theme manager for Java Swing programs. It allows the end user to select from pre-installed themes, or color schemes, or to create his own by the use of the ThemeEditor.

steelme is designed to be lightweight and easy for the application developer to use.

General Package/Module Interface (GPMI) is a lightweight library that assists with modularizing applications.
It includes prewritten script interpreter modules in addition to timers, events, and package dependencies.
Enhancements:
- This version features many bugfixes and memory leak cleanups.
- It is now possible to compile the code on Windows using mingw.

Golem is a lightweight, fast window manager for X11 which is very customizable.
Golems development has stagnated for a while and Jordan has given the project to Bruce Ashfield. Bruce is currently working on a new release which will have some existing patches applied.
Main features:
- Small memory footprint
- Window decoration customization (Themes) with multiple decoration styles (dgroups)
- Multiple disjoint large virtual desktops
- Hotkeys
- Supports various focusing styles (sloppy, pointer, click)
- Useful stuff for multiscreen displays (special focus cycling modes, etc)
- Xinerama support for multimonitor screens
- Plugins

Bungmeter project is a small network graph monitor.
Bungmeter is fork of fnetload. Its a small network graph monitor that displays a graphical representation of the the data flowing in and out of a given network interface. Its designed to be small and lightweight.
Enhancements:
- The code was updated to compile with GTK+ 2.8.x.
- A memory leak was fixed.

gLabels is a lightweight program for creating labels and business cards for the GNOME desktop environment.
gLabels project is designed to work with various laser/ink-jet peel-off label and business card sheets that youll find at most office supply stores.
Whats New in 2.0.4 Stable Release:
- This release primarily fixes a couple of crashes when built on GNOME 2.12.
Whats New in 2.1.4 Development Release:
- This development release features a large overhaul of some of the underlying technologies.
- This includes migrating to GtkPrintOperation, Cairo, and Pango.