The SDSS has proven to be an excellent dataset for exploring various problems in astrophysics and cosmology using weak lensing, with the highest lensing signal to noise to date and spectroscopic redshifts for lens galaxies, which simplifies theoretical interpretation by allowing us to compute signal as a function of transverse separation rather than angle. In this talk, I will describe our new Reglens reduction method that is used to measure galaxy shapes, discuss constraints on systematic errors, and describe several interesting science results that have resulted from it. Recently, we have placed constraints on dark matter halo ellipticity, and detected intrinsic ellipticity density alignments that may be important contaminants of current and future weak lensing surveys. I will also describe ongoing work such as a measurement of the dark matter power spectrum using a combination of galaxy-shear cross-correlation and galaxy-galaxy autocorrelation techniques; a study of the relationship between stellar masses, luminosities, and dark matter halo masses as a function of morphology and local environment; and the determination of average halo profiles using the lensing signal around field galaxies.