I've been ill this week. The only hacking I've been doing is of the cough variety. :) I think I'm recovering, though.
This evening, I finally checked out LibreOffice, to get an idea what's going on - kicked off a build, joined the mailing lists. Some of the easy hacks look quite feasible, but there's always a bit of work to get started. The community looks very welcoming, though, so no problems there.
The various Perl bits in the installer/build system seem an obvious place to get started. I've also got an eye on the mdbtools code - I theoretically maintain the Debian package, and have come close to forking it. But I aspire to be writing "real" patches, of course.
I've been thinking about where I should put my development time over the next year or so, and LibreOffice is likely to be one of those places.