Add ability to alter node content after field mapping prior to node submit

It's possible I'm missing something - if this exists already just point me in the right direction! What I'd like to do though is have the ability to post-process the field data after mapping is complete but before the node is saved. While I could probably accomplish what I'm looking to do through hook_nodeapi() it would be nice to have this added into Feeds in some way to have a bit more direct access.