Sigma SD1 Merrill has a Sigma SA Bayonet lens mount and currently there are 77 native lenses available for this mount.
The latest released lenses that are compatible with the SD1 Merrill are the Sigma 70-200 F2.8 DG OS HSM S, the Sigma 28mm F1.4 DG HSM A and the Sigma 40mm F1.4 DG HSM A.
Sigma SD1 Merrill doesn't have a sensor based image stabilization system but
30 of these lenses already comes with optical image stabilization.
Since Sigma SD1 Merrill has a APS-C sensor, it has a focal length multiplier of 1.5× so you have to multiply lenses original focal length with this multiplier to find the Full Frame equivalent focal length of the lens when mounted on SD1 Merrill.
You may also also be interested in these:
Sigma SD1 Merrill Lenses with Image Stabilization
Sigma SD1 Merrill Lenses with Weather Sealings