Since the advent of the Winbond BH5 chips about two years ago, no other memory chip has as large a claim to fame as the BH5. Those chips could run at 250MHz (500MHz DDR) at the tightest timings possible - 2-2-2-5!
Nothing else could match its performance and while the debate still rages on whether a high clock speed negates the need for tight timings, I for one am of the position that there is nothing more important than tight timings. Everything just feels snappier at tight memory timings.
As such, I have gone through several Winbond BH5 modules with my most recent modules as a pair of Corsair TwinX3200LLPT v1.1 modules. These modules managed to reach 250MHz at 2-2-2-5 timings with a voltage of 3.5V. Not the best of modules, but decent enough for BH5 modules.
For a full database of Winbond BH5 weeks and their relative performance, take a look at this forum thread.
Recently, OCZ Technology came out with their latest memory modules - the OCZ Enhanced Bandwidth series. It was discovered that these modules used the Micron Rev5B "C" memory chips.
Their performance was truly amazing at the timings of 2.5-2-2-5, instead of the commonly used timings of 2-2-2-5. Overall, they were at par with BH5 modules because they were hitting 250MHz at 2.5-2-2-5 with the voltage at around 3.2~3.5V.
I was lucky enough to spot a pair of 512MB modules featuring these amazing Micron modules. It's quite well-known that getting such memory modules are a bit of a gamble as some may do well while others may just be duds.
I took the gamble anyway and bought them. They are unmatched pairs in fact, as you can see below.