NBC's late-90s Saturday-night shows, The Pretender
, crossed over with each other a couple of times. I watched the former regularly, but not so much the latter, and I remember viewing the two-part crossovers when they aired back-to-back.
I was a little disappointed that The Pretender
DVD sets didn't include the Profiler
episodes that crossed over, but each one was somewhat self-contained (although I seem to recall the Profiler
episodes revealing new facts about the common plot-line), so I suppose it doesn't really matter in the long run.