With the advent of internet (and common sense) there is more and more demand for open-access research. Several researchers (including me) find it frustrating that published peer-reviewed research articles are behind paywalls. I am looking for journals and conferences (related to theoretical computer science, graph theory, combinatorics, combinatorial optimization) that make all accepted publications freely available to everyone.
If you know more such journals (or) conferences, please mention them in your answers.
EDIT : As suggested by David Eppstein in his answer, I am adding one more constraint. Please write only those journals/conferences that do not charge authors exorbitant fees to publish.