.NET Logging Framework
The logging framework provides you with an easy means to log information to any destination. It comes complete with loggers that support writing to the system console, a file on disk, a TCP/IP socket, and more.

AppLog
AppLog is a simple application logging utility. It is written in C#, and makes use of the ByteFX MySQL data access library. It is designed to communicate with a central MySQL server, and logs the following information: application name, user who is currently logged in, machine name, and application start time. AppLog will log only applications provided in a config file.

ASPNETWatchDog
ASPNETWatchDog is a suite of .NET components/services that enable you to log ASP.NET HTTP responses and watch them online or play back later. ASPNETWatchDog provides ASP.NET Developers/Administrators an easy way to capture/monitor/replay the activities

C# .NET Logger
Extensible .NET Logger written in C#, w/ advanced message queuing allowing for complete asynchronous use. Core system is in place with simple text logging.

C# Logger
The C# Logger is designed after the log4j project by apache. It is a logging tool that can be used to write events such as debug, info, warn and error messages to the Windows event log.

log4net
log4net is a tool to help the programmer output log statements to a variety of output targets. log4net is a port of the excellent log4j framework to the .NET runtime. We have kept the framework as similar to the original log4j as possible while taking advantage of new features in the .NET runtime. For more information on log4net see the features document.

Logger.NET
Logger.NET is a logging framework which enables you to include code which contains logging information (like Entermethod, Exitmethod, variable values etc) to be logged.

logthis
LogThis C# logging framework is a drop-in logging tool module for .Net applications. Supports: Multiple custom profiles; log file naming by day, week, month; max log file size; Windows event log. Simple out of the box, intelligent presets.

NAT Monitor
A tool to monitor internet hosts` bandwidth usage in a Linux-NAT network. A daemon collects data and clients display them (currently a GTK apps with a graph, a console version and a Win32 frontend). It detects new hosts and has a nice summary statistic.

NLog
NLog is a .NET logging library similar in concepts to log4net, designed with simplicity and flexibility in mind. Features: .NET, .NET Compact Framework and Mono 1.0 support; very easy to configure, both with a config file and programmatically; easy to use - interface is identical to Console.WriteLine - there's no need to use String.Format any more