Hello Andrew,
Currently there's no script repository or collection available.
Most of scripts that we have were created for special tasks (by user requests or for our internal needs), so they require description that could be even longer than the script itself. Another reason why we do not put all the scripts online, the need to keep them up-to-date. Sometimes PhotoScan Python API changes and older scripts need to be modified according to such changes, but keeping the entire collection updates is not reasonable, since most of scripts will not be used due to their specifics.
But still we have Python scripting sub-forum here and will surely help any PhotoScan user that require some assistance in script creation.