Theorem of the Day
The links below will bring you (in a new window) a superb collections of sites, blogs, online magazines etc, covering large parts of mathematics. Some subject-specific links are here.
This site draws inspiration from:
Nathan W. Kahl has posted a list Top 100 Theorems, attributed to Paul and Jack Abad but enhanced with many well-chosen links. The site appears now to exist only as an archive but the idea has been given new life by Freek Wiedijk whose list of formalised theorems I believe to be an important and forward-looking resource.
Another site offering infinitely many theorems ... named after you!
Mathematics Compendia & Encyclopediae
Cut-the-knot: Alexander Bogomolny's cornucopia of maths applets and animations.
Library of Math by David Andrew Smith
Mathpages by the admirable but elusive Kevin Brown
Numericana is an Aladdin's cave of answers to mathematical questions, basic and advanced, maintained by Gérard P. Michon. The Numericana Hall of Fame links to some of the best web resources in mathematics (I wrote that before Dr Michon was kind enough to include theoremoftheday.org in it!).
Eureka, the famous magazine of Cambridge's Archimedeans. The aim is gradually to make back issues available online; there isn't much there yet but it is worth checking from time to time.
The Feature Column of the AMS, currently edited by David Austin, Bill Casselman, Joe Malkevitch and Tony Phillips, has an brilliant archive going back ten years, with well over 100 authoritative articles.
Kömal Hungarian language magazine.
MATEMATICALIA Spanish language magazine.
Mathematics Magazine Canadian magazine for high school students.
Nieuw Archief voor Wiskunde Dutch language magazine.
Pythagoras, Dutch language magazine.
Resonance, general science magazine but with many interesting articles on mathematics.
Solmu, Finnish language magazine.
John Baez's Stuff – blogs, diaries, news; one of the greats!
Cameron Counts – a top professional gives an unusually wide-ranging view of the profession.
Carnival of Mathematics – an ingenious idea to showcase mathematics blogs.
Combinatorics and More – a beautiful blog by Gil Kalai.
CSE Blog – fun place for puzzles, tricks, tips on quantitative methods by Pratik Poddar.
Tanya Khovanova's blog –"mathematics, applications of mathematics to life in general, and my life as a mathematician". Fun and sometimes funny and sometimes weird.
learninginmathland – a blog for teachers (and their students and anyone else who appreciates seeing the basics lovingly and expertly presented).
Mathblogging: latest posts from hundreds of maths blogs.
Terence Tao's research blog – the one I hear PhD students talking about all the time...
XOR's Hammer – a wonderful blog by Michael O'Connor, primarily about mathematical logic, but with lots and lots of other nice things
alwaysmath.com/ pre-kindergarten to college level math: a kind of online home tutor; lots of multiple-choice tests etc.
images.math.cnrs.fr, great blog-style collection of images and words (in French) — à ne pas manquer!
Just The Maths, a superb teaching pack for 'mathematical methods' by A.J. Hobson. The distillation of a lifetime's thinking about how it should be done.
The M500 Society, one of the UK's great unsung mathematical resources, going from stength to strength after 35 years and the source of the beguiling M500 Magazine.
mangahigh.com, a commercial-quality computer games site for school-level maths. Very impressive!
Math Forum, an excellent resource for schools and colleges.
Math Insight, a tremendous collection of notes on mainly analysis-related topics.
NRICH brings mathematics alive for school students like nowhere else.
Onlinemathdegrees.org a valueable (currently USA-oriented) listing of undergraduate opportunities in mathematics.
The Peoples Archive has film+transcript interviews with a galaxy of intellectual and artistic giants, including Miachael Atiyah, Freeman Dyson, Don Knuth, Benoit Mandelbrot.
Travels in a Mathematical World: podcast site, a great source of live interviews, bits of mathematical history etc. Peter Rowlett has moved on (see above) but the site will remain, and remains a valuable visit.
Virtual Maths Museum: a fine collection of images of curves, surfaces etc.