I'd like to say that, as a perl guy without a comp sci background, the only places I get this sort of information are Mastering Algorithms in Perl and nodes like these here, so I really appreciate them. Off to Wikipedia to read more, I suppose.

"(Note that "heap" can also refer to an area of memory used for dynamic memory allocation.)" - This was useful because I came in here expecting databases stored in memory, and you were starting to weird me out talking about btrees :).