As an undergraduate (and for a brief period once I graduated), I worked on areas of discrete math, including Venn diagrams. In fact, I helped develop the constructive proof that rotationally symmetric Venn diagrams existed for all prime numbers of curves . Note that for non-prime numbers of curves, rotationally symmetric Venn diagrams are known to not exist.
However, these diagrams (graphs) are not “simple”. A bit later, I helped Ruskey, Savage, and Weston prove that you could produce “half-simple” rotationally symmetric Venn diagrams for prime numbers of curves . But it has remained unknown whether they could be simple. Today, I read that it has been shown that for 11 curves, they can be simple. See Ruskey’s writeup for pictures , or this blog post  by Adrian McMenamin for a discussion of what simplicity means and an overview of the technique.
Note that while I made my contributions, Ruskey and Savage are considerably more established in this area. Frank Ruskey is particularly well known for his work in graph algorithms. So when I talk about my part of this research, while I had my contributions, it is of course but one small part of the scientific process. It’s nice to see that this has continued, and to feel like I was part of helping make this happen.
 Jerry Griggs, Charles Killian, and Carla Savage. Venn diagrams and symmetric chain decompositions in the Boolean Lattice. Electronic Journal of Combinatorics. Volume 11, January 2, 2004. [http://chip.kcubes.com/research/venn/v11i1r2.pdf] (An article about this result appeared in Science, Vol. 299, January 31, 2003 and it was the subject of a front page article in the January 2004 issue of SIAM News. Additionally, this work was featured in the December 2006 issue of the Notices of the AMS.)
 Charles Killian, Frank Ruskey, Carla Savage, and Mark Weston. Half-Simple Symmetric Venn Diagrams. Electronic Journal of Combinatorics. 2004. [http://www.cs.uvic.ca/~ruskey/Publications/HalfSimple/HalfSimple.pdf]