(Non-Debian readers can stop reading now, I'm talking about so-called "orphaned packages" and not anything of real-world importance.)
In 2008 I stopped maintaining non-native packages in Debian. At the time I maintained a fair amount of stuff. It's interesting to see what happened to it after I gave it up, partly because some of the results seem so random and partly because some of what has happened seems to point at weaknesses in Debian.
First, the success stories. More than half of my packages are now being maintained by others: xaos, longrun, fbreader, liblinebreak, analog, xgalaga, znc, sysnews, metastore, bsdgames, uqm, oneko, kobodeluxe, archivemail, unclutter I still use much of this stuff, some only occasionally, and other daily, and am glad it's being kept alive. (It's surprising that someone still care about longrun.)
I was unhappy to have to NMU procmeter3 just before the release of Debian 6.0 to fix a trivial to debug RC bug that almost got it removed from the release. I hope that was just a bump in its road.
Also, splitvt is now maintained again after being orphaned a long time. I'm not sure if it makes sense to keep it in Debian, since screen can do the same thing, and it has a security history, but someone wants to, so that's fine.
Two packages are left on life support. I'm surprised nobody wants to maintain grepmail, unless we're all using notmuch or mairix now? And dgen is the best Sega emulator I know of.
Several games were not picked up by the games team, despite them showing some interest originally, and were removed: xtris, xjewel, xemeraldia, xbl Of those, xemeraldia in particular is a lot of fun, I'm surprised nobody cared to keep it. Also, the nestra Nintendo emulator was shipped with squeeze, but now is removed as it never got a maintainer. I don't know if there is a better NES emulator in Debian.
The intercal programming language was removed. Surprising. Debian does at least still have clc-intercal for all our pressing Intercal needs.
Finally, sparkline-php was removed today despite never having had any bugs, needing no maintenance, and being a suggests of ikiwiki, which is now more buggy (broken relationships, outdated docs) and less featureful in Debian.