The Polish memory producers have a huge 4GB 900MHz kit to offer.
The fastest available 2x2GB kits we know of work at 800MHz, but GOODRAM/Wilk Elektronik designers managed to squeeze an additional 100MHz out of their modules. Of course, DDR 2 900 memory will work at CL5 but this is quite good for this speed and 2GB modules.
The GOODRAM PRO modules also look very nice, with orange heatsinks and engraved white markings. The "regular" PRO series products have blue heatsinks with white markings. We hope to get our fingers on one of these soon.