This may not apply to your language, but some projects could be maintained by making sure the newest compilers don't throw warnings. In my experience every once in a while when I try a new version of clang on my project, there will be some new warning showing up due to improved diagnostics. Even if not, grab some new tool and check your source - then say you've done it. Some ideas: (for a C project)

- warnings under GCC, clang

- valgrind (commit suppressions of needed, note there are no issues left)

- clang static analyser

- fuzz inputs, commit a note about what was tested

- does it already compile under Linux? Each main distribution? BSDs? Windows? Mac?

- does it include init scripts? Upstart config? Systemd?

- apparmor and selinux profiles?

- have you tested new versions of all your dependencies?

I'm sure not all points will apply to your project, but just be creative with those ideas :-)

Just do something useful. All of those points being some benefit to the project, even if tiny.