One of the biggest problems I have as a dm is keeping track of which monsters are which during an encounter. Often you have 5 monsters with the same name and use similar minis for each of them. When these monsters move and throughout battle sometimes its easy to lose track of which one took 30 damage and which one took 25. The most elegant solution I've seen for this can be found at http://stuffershack.com/store/ they sell little counters with numbers on them that can be attached easily to minis with sticky putty (which you can find at any walmart or office supply store) these counters mean you can simply number your monsters easily and know which ones are which at a glance.
They also sell little red counters for indicating bloodied enemies, a nice touch. Also horses with large bases so you can attach characters to the base of their horse. This makes mounted combat much easier.