I've just come across a fairly basic online vector editor. Definitely a handy web app for creating basic vector work. I imagine it only works on more recent browsers.
The vector editor can be found at: http://editor.method.ac/
The person/company that produced that free open source app, have also produced a few apps for becoming better at design both technically and theoretically.
I think these are immense contributions to the design community and for that reason I am including the links in plaintext because I heard that the no-follow rule doesn't apply. It is not a commercial enterprise so I think it's OK.
Get better with the Pen tool with a simple and fun game: http://bezier.method.ac/
Learn more about kerning with another game: http://type.method.ac/
Learn about shaping letters in typography with another game: http://shape.method.ac/
Test your colour matching skills with another game: http://color.method.ac/