(What is strange is wonderful.)
Below is a number of resources everybody working on mathematical physics related to string theory should know.
You should make a habit of checking new papers appearing on the arXiv in hep/th and math/ph every day. Also, use review papers and lecture notes published on the arXiv to learn new topics.
THE database for publications related to high-energy-physics and string theory is inSPIRE, which allows you to access various versions of papers and find references and citations.
The nLab is an incredibly rich and useful resource. The requirements for understanding many entries are sometimes a little high, but once you're happy with the language (mostly higher category theory), you don't want to look back. The nLab contains mathematical definitions/theorems/literature as well as entries on topics in string theory and mathematical physics. The latter are usually phrased in the appropriate mathematical language one should use.
Do an online search for PhD theses to learn new topics. They often contain nice explanations at your level. Before reading a paper, search for corresponding online seminar talks (maybe even on YouTube) and have a look at them.
A huge collection of lecture notes and review papers in all areas of physics can be found at The Net Advance of Physics.
This week's find in mathematical physics by John Baez. A classic, unfortunately discontinued. The perfect site to read when you're procrastinating from your actual research. At least time is not wasted there
Find and read some online style guides and writing tips for scientists. Try to write every day a bit. Don't have too many paper notes around, LaTeX them. It doesn't take as much time as you think it does. If you publish with me, please follow my Style Guide. The latter is work in progress and constantly updated. Suggestions for improvement are welcome. Also, please use my BibTeX Style File.
The Lab Notebook
Here is my "Lab Notebook". This is a very rough and unpolished collection of references, definitions, results, descriptions, formulas and other useful things for me and my students. A lot is copy/pasted from my papers and lecture notes. This is very much work in progress never meant to be original. Suggestions for improvement and corrections are very welcome.