I'm at Cruft Force 3 going on 4, but then I have a fairly new PC.
Via iamcal.
Reference Objects and Garbage Collection By Monica Pawlan.
See also O'Reilly on the WeakHashMap class, and an implementation of SoftHashMap, which is missing from the Sun library.
Weak references exist in Python, but unfortunately soft references do not. Which is a shame, 'cos they are very useful for eliminating memory leaks from data caches.
This is every parent's nightmare. It's at times like this that I wish I was a theist, so that I could prey for them.