Paper 'Young Flattenings in the Schur module basis' (with Lennart Haas) with source code: [ arXiv ]
Source code for the paper 'Equations for GL-invariant families of polynomials': [ GL-paper ]
A Java implementation of algorithms for computing Littlewood-Richardson coefficients: [ source ]
The corresponding papers are 'Deciding Positivity of Littlewood-Richardson coefficients' (with Peter Bürgisser) and 'Small Littlewood-Richardson coefficients'.