DDR3 Maximum Overclocked Speeds - PCSTATS
DDR3 Memory - Maximum Speed w/ Low Latency	Timings	Capacity	Max Speed	Ranking
Corsair DOMINATOR Twin3X2048-1800C7D	7-7-7-20	1024MB	1840 MHz
Super Talent W1866UX2G8	7-7-7-20	1024MB	1780 MHz
Mushkin HP3-10666	6-7-6-18	1024MB	1452 MHz
Crucial Ballistix PC3-12800	7-7-7-20	1024MB	0
DDR2 Memory - Maximum Speed	Timings	Capacity	Max Speed	Ranking
Corsair DOMINATOR Twin3X2048-1800C7D	8-8-8-24	1024MB	1920 MHz
Super Talent W1866UX2G8	8-8-8-24	1024MB	1900 MHz
Crucial Ballistix PC3-12800	8-8-8-20	1024MB	1780 MHz
Mushkin HP3-10666	8-8-8-24	1024MB	1760 MHz

DDR3 memory is in its infancy and PCSTATS has not tested that many modules yet. Still it's nice to see how the four modules scale with tight and loose memory timings. The memory is listed in what is fastest for each criteria and more are coming...

DDR2 Memory:

DDR2 Maximum Overclocked Speeds - PCSTATS
DDR2 Memory - Maximum Speed w/ Low Latency	Timings	Capacity	Max Speed	Ranking
Corsair DOMINATOR Twin2X2048-8888C4DF	4-4-4-12	1024MB	1260 MHz
Corsair DOMINATOR Twin2X2048-8888C4DF*	4-4-4-12	1024MB	1244 MHz
Patriot PDC22G9200ELK	4-4-4-12	1024MB	1170 MHz
OCZ PC2-7200 Platinum SLI*	4-4-3-15	1024MB	1142 MHz
Corsair DOMINATOR Twin2X2048-9136C5D*	4-4-4-12	1024MB	1142 MHz
PNY XLR8 D22GX85XL-5	4-4-4-12	1024MB	1120 MHz
A-DATA Vitesta Extreme Edition	4-4-4-12	1024MB	1100 MHz
Patriot PDC24G6400LLK	4-4-4-12	2048MB	1066 MHz
Mushkin XP2-6400	4-3-3-10	2048MB	1066 MHz
SuperTalent T1000UX2G4	4-5-4-12	1024MB	1044 MHz
Corsair Twin2X2048-6400C4*	4-4-4-12	1024MB	1000 MHz
Patriot PDC22G8000+XBLK	4-4-4-12	1024MB	1000 MHz
Corsair Twin2X2048-8500C5*	4-4-4-12	1024MB	977MHz
Crucial PC2-6400	4-4-4-12	1024MB	890 MHz
Corsair Twin2X2048-6400C3*	3-4-3-9	1024MB	888 MHz
PNY D22GX93XLP-5 XLR8	4-4-4-12	1024MB	N/A
DDR2 Memory - Maximum Speed	Timings	Capacity	Max Speed	Ranking
Corsair DOMINATOR Twin2X2048-8888C4DF	5-5-5-15	1024MB	1300 MHz
PNY D22GX93XLP-5 XLR8	5-5-5-15	1024MB	1280 MHz
Patriot PDC22G9200ELK	5-5-5-12	1024MB	1260 MHz
A-DATA Vitesta Extreme Edition	5-5-5-15	1024MB	1250 MHz
Corsair DOMINATOR Twin2X2048-8888C4DF*	5-5-5-15	1024MB	1244 MHz
Corsair DOMINATOR Twin2X2048-9136C5D*	5-5-5-15	1024MB	1244 MHz
PNY XLR8 D22GX85XL-5	5-5-5-15	1024MB	1220 MHz
OCZ PC2-7200 Platinum SLI*	5-5-5-15	1024MB	1219 MHz
Corsair Twin2X2048-8500C5 *	5-5-5-15	1024MB	1200 MHz
Patriot PDC24G6400LLK	5-5-5-15	2048MB	1180 MHz
SuperTalent T1000UX2G4	5-5-5-15	1024MB	1160 MHz
Patriot PDC22G8000+XBLK	5-5-5-15	1024MB	1155 MHz
Corsair Twin2X2048-6400C4*	5-5-5-15	1024MB	1142 MHz
Mushkin XP2-6400	5-5-5-15	2048MB	1130 MHz
Crucial PC2-6400	5-5-5-15	1024MB	1080 MHz
Corsair Twin2X2048-6400C3*	5-5-5-15	1024MB	1066 MHz

* - denotes tested on ECS PN2 SLI2+ platform

There's a bit more information available for the DDR2 memory modules like what CAS latencies the memory are able to run at what speeds. The various modules are ranked by maximum speed with both tight and loose memory timings.