http://www.ultrasem.org/
ultraSEM is MATLAB SEM software based on the ultraspherical spectral element method; a sparse spectral element method based on the hierarchical Poincare–Steklov scheme suitable for hp-adaptivity with very high p.

https://github.com/ajt60gaibb/freeLYAP/
A free and open-srouce implementation of MATLAB's lyap() function for solving Sylvester and Lyaponov equations.

https://github.com/nickhale/alignfigs/
Short MATLAB code to align all open figure windows in a tidy grid formation..

https://github.com/nickhale/leg2cheb/
A fast algorithm for converting between coefficients of a Legendre series expansion and a Chebyshev series expansion. Based upon the work in N. Hale and A. Townsend, A fast, simple, and stable Chebyshev-Legendre transform using an asymptotic formula, SIAM Journal on Scientific Computing, (submitted 2013)

https://github.com/nickhale/quadpts/
Fast and accurate computation of Guass-Legendre and Gauss-Jacobi quadrature nodes and weights via asymptotic formulae. Based upon the work in N. Hale and A. Townsend, Fast and accurate computation of Gauss-Legendre and Gauss-Jacobi quadrature nodes and weights, SIAM Journal on Scientific Computing, (2013).

http://people.maths.ox.ac.uk/trefethen/bmi_calc.html
Basic javascript implimentation of Prof. Nick trefethen's proposed modification to the formula for computing Body Mass Index (BMI), which received a not insignificant amount of attention in the media during January 2013.

As part of my masters degree I reimplented the MATLAB ODE solver bvp4c using a 6th-order interpolant (hence, bvp6c). You can find out more about this in my masters thesis.

https://github.com/nickhale/
The list above is probably out of date.. See my GitHub page for more software.