People generally start new threads for UOAs around here, though I think a central repository is a pretty good idea. I'll get things started with some links to UOA threads I can find easily.
My UOA history is
HERE. Currently 45k mi worth.
My Father's UOA history in his Outback 3.6 is
HERE. 50k mi and counting.
Dennis (bluesubie) posts a new thread for each uoa in his '04 Forester XT. He also changes oil brand/type like women change clothes.
M1 0w40 UOA
Motul X-Lite 0w30 UOA
Pennzoil Ultra 5w40 UOA
Another UOA with M1 0w40
Amsoil SSO 0w30
Amsoil SSO 0w30 #2
Castrol Syntec 0w30
Motul 8100 5w30
Castrol Syntec 0w30 #2
Castrol Syntec 0w30 #3
Castrol Syntec 0w30 #4
Castrol Syntec 0w30 #5
And finally M1 10w30 in Dennis' old WRX