Ha! Some people are so bloody ungrateful. I personally, like Eidolon, would appreciate decent advance notice. It seems like eukhost's past experience with angry customers opening tickets was simply a result of eukhost's courtesy and a few customers' stupidity.
It's a shame that these customers weren't more circumspect before they opened tickets.
Eidolon, one option for you might be to use a domain manager program on your desktop to make sure you don't forget to advise clients to renew. Try
http://www.download.com/Domain-Name-...-10604445.html for a free decent manager although just typing in 'free domain manager' on an SE will get you loads of results.