clearclimatecode.org is a project of Nick Barnes, who occasionally comments here. Its an attempt to re-write the byzantine GISS historical record processing software into something that won’t disgrace the 21st century, namely Python (boo hiss, but mt will be happy).
So the bugfixes are nice and clearly described, and are things like “STEP 0 of the GISTEMP code is in FORTRAN. This makes it unclear to the public.” :-)
The aim is to re-implement the GISS algorithms, but in clearer code and in a more portable way, ideally producing identical results except for bug-fixes.
They have found one real bug so far: “GISTEMP STEP0 discards the final digit of every USHCN datum”. Before anyone gets overexcited, GISS already know, have fixed it, and it makes no noticeable difference to the overall result.
Someone else, I think, was doing an open data averaging project, but I forget where. [Update: www.opentemp.org by John Van Vliet (thanks IH). Not sure if that is still active -W]