I don’t know how many times I have had to deal with the situation where a system requires some module that is built separately from the kernel tree (such as OpenAFS and NVIDIA drivers) and a kernel upgrade is installed either automatically or as part of an upgrade set, leaving a surprise for the next reboot when the module for the new kernel version does not exist. (Other Debian users have reported similar gripes.)
I came up with the following solution. It uses module-assistant to automatically build every kernel module package whose source is currently unpacked in /usr/src/modules.