The Creative Commons license option I chose (Creative Commons Attribution-Noncommercial 2.5 License) allows you to reuse these cartoons as long as you make clear the license terms of this work (that’s why I insert the Creative Commons logo).
More on this specific license here: http://creativecommons.org/licenses/by-nc/2.5/
In short (took this from the link above) you are free to:
to Share — to copy, distribute and transmit the work
to Remix — to adapt the work
Under the following conditions: Attribution — You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work). Noncommercial — You may not use this work for commercial purposes
This means you can share or reuse (for example convert it in another format – put it in a t-shirt!, mix it, use it in a presentation…) as long as you don’t make money of it and you attribute the work to the author (in this case you are free to change the licensing terms of your derivative work because I wanted people to have that option). For other scenarios, then one just needs to talk about it and define a specific agreement.