Pierre La Riche, author of the FastMM4 memory manager I already discussed in this blog, has written an article for BDN (Borland Developer Network), covering the core technical features of the memory manager.
If you are using the new memory manager in Delphi 2006 or have added it to earleir versions of Delphi, this is a recommended reading. If you are still using Delphi's traditional memory manager, it is even more recommended... as you should switch as soon as possible.