[Draft version! Beware!]

Mathematical Resources

Your first port of call will often be in the form of electronic resources.  One of the most important of these is mathscinet

The Mathematics ArXiv is the most important source of preprints on the web.  This is part of a larger collection of preprints, including physics and computer science.  Another useful source of computer science preprints is the Electronic Colloquium on Computational Complexity.  It's also sometimes of interest to look at conference proceedings, for instance Lecture Notes in Computer Science.

For general news on combinatorics events in Europe, I recommend subscribing to DMANET.

Journals

I used to spend a lot of time in libraries, browsing through journals.  Probably much of it was a waste of time, but I did read a lot of abstracts, and I still like to know what the physical version of a journal is like.  It's interesting, too, to browse through new journal issues, and to get some sense of what sort of material a journal carries through the years.  All of this is used to be best done by visiting the library in person.  However, it also takes a lot of time, and you can now look through journals, and much of the time get papers, without leaving your desk (or even getting out of bed, if you have a laptop and a wireless network).

Some journals now have RSS feeds, but this is only gradually becoming standard.  Inside Oxford, there is a list of mathematics journals produced by the Whitehead library; the full Oxford e-collection is indexed here.

There are loads of journals around, but the main combinatorics journals that I look at regularly are:

Combinatorica
Combinatorics, Probability and Computing
Discrete Applied Mathematics
Discrete Mathematics
Electronic Journal of Combinatorics
European Journal of Combinatorics
Graphs and Combinatorics
Journal of Combinatorial Theory, Series A (commonly known as JCTA)
Journal of Combinatorial Theory, Series B (or JCTB)
Journal of Graph Theory
Random Structures and Algorithms
SIAM Journal on Discrete Mathematics

Other interesting journals include:

Annals of Combinatorics
Computational Geometry
Discrete and Computational Geometry
Discrete Maths and Theoretical Computer Science
Discrete Optimization
Information and Computation
Information Processing Letters
Internet Mathematics
Journal of the ACM
Journal of Computer and System Sciences
Journal of Discrete Algorithms
Networks
OR Letters
Order
Probability Theory and Related Fields
SIAM Journal on Computing
SIAM Review
Theoretical Computer Science

The ACM (Association for Computing Machinery) also has SODA proceedings and SIGACT.

And here are some journals that are occasionally interesting (or that I want to remind myself about for some reason):

Complexity
Contributions to Discrete Mathematics
Electronic Notes in Discrete Mathematics
Journal of Combinatorial Optimization
Journal of Interconnection Networks
Linear Algebra and its Applications
Mathematics of Computation
Periodica Mathematica Hungarica