FieldTrip is the Matlab software toolbox for MEG and EEG analysis that is being developed at the Donders Institute for Brain, Cognition and Behaviour at the Radboud University Nijmegen, the Netherlands together with collaborating institutes.
It supports the data formats of all major MEG systems (CTF, Neuromag, BTi) and of the most popular EEG systems, and new formats can be added easily. It contains high-level functions that you can use to construct your own analysis protocol in Matlab. Furthermore, it easily allows developers to incorporate low-level algorithms for new EEG/MEG analysis methods.
The FieldTrip software is released as open source under the GNU general public license.