TodoBG is a Python script for the GNOME desktop that I hacked up to make using my todo.txt easier to maintain. Instead of keeping a separate window/vim session open with the todo list inside, this script reads the contents of the todo.txt and creates an image that you may set as your background (in GNOME, the background is refreshed pretty quickly).

I got tired of having to clean out my programs list one by one on my Windows boxen, so I hacked this guy up to make it a bit easier. Works on 2000, XP, and Vista. I don't know about earlier versions. Requires Mono 1.9 or .NET 2.0.

On Vista and above, right click -> run as administrator.

I always wanted a nice program to tell Windows when to boot into safe mode rather than have to sit as it reboots and tap F8. This uses the Boot.ini (so it doesn't work on Vista) to tell Windows how to boot the next time. You can also force a chkdsk if you want. Requires .NET 2.0 or Mono 1.9. Only tested on XP and 2000.

Given various ways of building paths, which is fastest? Or uses less RAM/GC?
Written in C#

Project Euler is a website with ~200 math problems/puzzles that are meant to be fun to solve. I enjoy solving problems like them, so this is where I will post the source to the problems I solve.

The ClamAV LiveCD was a CD I created while I was working at the computer repair shop to scan computers for viruses. It was a small CD (around 120 MB). The traditional way (take the hard drive out, stick it in another computer, scan it, take it out, put it back in) was extremely cumbersome and was a big bottleneck since we could only scan 2 HDD's at once (1 SATA, 1 IDE). With this CD, I was able to scan as many computer as I wanted, even remotely with SSH.

 
Please see http://volatileminds.net/opendiagnostics/index.php/BuildAutoAssessmentServer to build a server that can run this script.
Latest source: http://code.google.com/p/od-autoassess/

This is actually a small contact-storing web app I had to develop as a test when I was applying at Gamestop (didn't get the job). Uses SQLite and is in C#/ASP. In order to pass the test, this had to be done in 24 hours and I finished it in 18 :-). I had never used SQLite in an app before this. I am pretty proud of this app. Ideally I would be using javascript rather than posting back all the time, but eh. 

I post this because I think it would be a great app to dissect and add onto if you are just learning or wanting to learn C#.

This is a legacy 4chan image mulcher that I wrote a while back in C#. It should no longer work (I believe moot has changed up his code since this was written) which is why I am releasing the source. It also used MySQL as the DB backend, but alas, I have lost the DB script. This was actually a very neat project. I wanted an automated way to mulch and display images from 4chan, and certain blog services allow you to email posts to it. This app mulched the images and saved them, then generated HTML and emailed the html to the blog service and a post was made. Setting the app on a cron job, everything was automated. This combined with LinkBucks, I actually had some steady (albeit not much) cash coming in when combined with some special Linkbucks code. Not enough to make it worth it to maintain the project. It should be fairly cross-platform. The server that ran it was Linux (using Mono) and was developed on Windows.

THC Hydra is a neat app that tries to bruteforce credentials using predefined wordlists for certain services (http/s, ftp, any major protocol). These are ubuntu debs of the app. 

This comes with both the CLI version (hydra) and the GTK gui (xhydra).

Homepage: http://freeworld.thc.org/thc-hydra/

This is a small benchmark that was written in the 80's by John Walker in C. I wanted to see the performance of Mono vs .NET arithmetically.