The Mathematics and Computation blog focuses on connections between mathematics and the theory of computation. The blog is owned and written by Andrej Bauer, with occasional guest posts.

Mathematics and computer science notes, includes continued fractions, elliptic curves and a lot more.
See also the link to the home page http://crypto.stanford.edu/~blynn/
where you can find some simple programs in both C and Go, a guide to the git version control system.

From the Overview:
Traditional mathematics teaching is largely about solving exactly stated problems exactly, yet life often hands us partly defined problems needing only moderately accurate solutions. This engaging book is an antidote to the rigor mortis brought on by too much mathematical rigor, teaching us how to guess answers without needing a proof or an exact calculation.

Available as printed book and creative commons licensed PDF file.

Good Math, Bad Math is a blog which exists for two reasons:
  1.  For me to ramble about the beauty of mathematics, and try to share my enthusiasm for the subject.
  2. To track down the bozos who use bad math to lie, distort reality, and in general support bad arguments; demonstrate their errors and their dishonesty; and generally mock them.

The blog will also intermittently include me rambling about other obsessions: programming, music, and whatever else interests me.

Since 2014-02-13, his blog is hosted on http://www.goodmath.org/blog

Interesting visualizations of irrational numbers.

On-line handwriting recognition for mathematical formulas, generates LaTeX and MathML and can pass on the formula to Wolfram Alpha.

Interesting information about numbers, the Mandelbrot set, Video effects/screen savers and RIES, an inverse equation solver (you provide a solution and it generates equations).

MIT Photonic Bands (MPB) electromagnetic eigenmode solver Meep finite-difference time-domain simulations Harminv extraction of complex frequencies and amplitudes from time series libctl Scheme/Guile-based scripting of scientific code (used as the interface for MPB and Meep). h5utils visualization of HDF5 data files NLopt nonlinear optimization library implementing many different optimization algorithms Cubature code for adaptive multidimensional integration of vector-valued integrands via the Genz-Malik algorithm. Faddeeva_w code to compute the complex error function (Faddeeva function).

Pancakes with interesting shapes. More can be found by following the links.

"Talk" by Ken Perlin about the use of noise in computer graphics.