Being my first guide this is for those already familiar with configuring conky.

Download the todo program I wrote from 

http://www.verdow.com/todo

make it executable and move it to /usr/local/bin

chmod +x ~/todo

sudo mv ~/todo /usr/local/bin

This will allow you to easily manage your to do list from the command line.  More on this later...

Create an empty ~/.todo file (this is where your list is actually stored) by running:

touch ~/.todo

Edit your ~/.conkyrc and create a heading if you want one.  I'm not posting an example for this since every .conkyrc will be different, just copy a heading from another line and replace the text with "To Do".  After that add this line to display the list:

${execi 2 cat ~/.todo}

Restart conky and you should see nothing but the heading.  To add items to your todo list simply run todo followed by whatever.  Ex:

todo Mow the lawn.

To remove an item use todo -r followed by a chunk of text from one of the lines.

todo -r lawn

The program uses grep to find the item to remove so you don't have to put in much.  If the text you entered returns multiple matches the program will warn you and nothing will be removed so you don't accidentally delete a bunch of stuff.

To rearrange the list you can send items to the first or last positions using the -f (first) and -l (last) switches.  These work similar to the -r switch; only a piece of the text is needed to move the item and multiple matches won't be moved.  If whatever you put after -f doesn't match any items it will be added to the top of the list so if you want to add an item straight to the top of the list without having to move it later, just use the -f switch when you create the item.  The -l switch doesn't do this since the default behavior is to add it to the end of the list anyways.

Some more examples:

todo read up on fire safety

todo play with matches

todo -l read (move "read up on fire safety" to the bottom of the list)

todo -f put out fire (create "put out fire" at the top of the list)

todo -r fire (returns an error, multiple matches)

todo -r put out (removes "put out fire")

todo check insurance coverage (adds "check insurance coverage" to the list)

todo -f safety (moves "read up on fire safety" to the top of the list) 

Feel free to dig around in the code, though go easy on me since this is my first-ish perl program (only Chapter 4 in Learning Perl) ;)