Proceedings of all past ICM-s can be found here: <http://www.mathunion.org/ICM>

The following [nlab](http://www.ncatlab.org/nlab/show/HomePage) pages

* <http://www.ncatlab.org/nlab/show/Online+Resources> -- a long list of math blogs and forums

* <http://www.ncatlab.org/nlab/show/math+institutions> -- main institutions 

* <http://www.ncatlab.org/nlab/show/math+archives> -- preprint/journal/book/review archives

<http://numdam.org> is a collection of old issues of many mainly French math journals. 
<http://www.mathnet.ru> site has links to free old issues of most of the Russian math journals (and even some video lectures) in Russian and links to some non-free English versions. There is also an English mode of the site: <http://www.mathnet.ru/index.phtml?&option_lang=eng>. A smaller free depository of old issues of Polish math journals is <http://matwbn.icm.edu.pl> (click on the flag for English).

Max Planck maintains links to a very long list of journals, most of which are proprietary and usable only from their site, but the list is still useful because a sizeable fractions of links are also to free journals or some volumes of journals which are free, and those are mainly usable from all locations. The current URL is <http://rzblx1.uni-regensburg.de/ezeit/fl.phtml?bibid=MPIMA&colors=3&lang=en&notation=SA-SP>

Many resources can be found at the sites of main world math institutes like [ihes](http://www.ihes.fr), [mpim-bonn](http://www.mpim-bonn.mpg.de), [Oberwolfach](http://www.mfo.de), [msri](http://www.msri.org), [kitp](http://www.itp.ucsb.edu), [ictp](http://www.ictp.it), [rims](http://www.kurims.kyoto-u.ac.jp/en/index.html), [ias](http://www.ias.edu), [Steklov](http://www.mi.ras.ru/index.php?l=1) 

[AMS](http://www.ams.org) keeps a long [list](http://www.ams.org/mathweb/mi-sao.html) of math societies throughout the world with links to their sites, which are often useful. One should also recommend more general AMS directory of links *Math on the Web* <http://www.ams.org/mathweb/index.html>.