I understand your pain!!!
My very first temptation is to say simply "GET A METRONOME, !@#$%!"

But +1 to Plangentmusic, "you can lead a horse to water" right?...
We deal with this problem on a weekly basis with our piano player at church. I've spent many many hours with a metronome or playing with phrase samplers, which are plainly unforgiving.
(currently a Boss RC-2, but I miss my Boomerang+ *sniff*) Because of that, I'm fortunate to have a good ear for time (and conversely, a good ear for timing
problems as well). The drummer isn't the most talented/flashy out there, but he's rock solid on tempo and
still keeps a metronome with headphones at his drums. It's clearly evident to both of us that the pianist hasn't spent nearly enough time with one (if at all). We try not to get on the guy's case though, the director does a fine job of that.
Seriously though, metronomes are one of the biggest overlooked items in a musician's toolbox, ESPECIALLY the rhythm section. When people have ask me how to get their kids started in music, suggesting a metronome is one of the first topics in the discussion!
Subscribed to see if anyone else has any good ideas!
5sg.