Some of the sites I enjoy:

Swedish BMW motorcycle club (in Swedish):

The biggest adventure site, can be a bit crowded:

Great UK site for BMW GS bikes:

Small but good r1200gs site:

Great Suzuki v-strom site (I use to have one):

BMW R1200GSA -08, Schuberth R1 with Bluesonic, Garmin Zumo 660 not working with Bluesonic Sad