What are some small, fast and lightweight open source applications (µTorrent -esque)? [closed]

Question

Possible duplicate
What is the best open source example of a lightweight Windows Application?

µTorrent is a small bit-torrent client, a really small one. It doesn't come with an installer, just a exe, you drop in your PATH somewhere. It's super lightweight and yet feature rich. Plus it is the work of one man. It's also closed-source.

Many people have been curious about how it has been written, and there are hints here and there about a custom library etc. But the question is, are there any programs with attributes like µTorrent that are available with source code--attributes like speed, small size, awesomeness.

Possible related question (/questions/9603/what-is-some-great-source-code-to-read), but think smaller than something like the Linux kernel.

Clarification: I don't want examples of bit-torrent source code, but anything which is used by tons of people (validation of awesomeness) and also fast, small and awesome!

Answer 1

I think you should take a look at Notepad++ if you want to see a feature-rich low-consumption of power software :)

Answer 2

Netcat It's the program that started all of the curiousity behind networks and how things WORK. Everyone's looked at this source code.