Electron-based light sources have proven to be effective sources of high brilliance, high frequency radiation. Such sources are typically either linac-Free Electron Laser (FEL) or storage ring types. The linac-FEL type has high brilliance (because the beam is microbunched) but low repetition rate. The storage ring type has high repetition rate (rapid beam circulation) but comparatively low brilliance or coherence. We propose to explore the feasibility of a microbunched beam in a storage ring that promises high repetition rate and high brilliance. The steady-statemicro-bunch (SSMB) beam in storage ring could provide CW sources for THz, EUV, or soft Xrays. Several SSMB mechanisms have been suggested recently, and in this report, we review a number of these SSMB concepts as promising directions for high brilliance, high repetition rate light sources of the future. Show Partial Abstract