Micro-segmented flow (e.g. in microfluidic channels, capillaries or a length of tubing) has become a promising technique in modern biology. Compared to conventional formats such as microtiter plates, sample volumes can be reduced about 1000-fold, thus allowing a massive reduction of assay costs and the use of samples available in low quantities, only (e.g. primary cells). Furthermore, assays can be highly parallelized and performed at superb spatio-temporal resolution. Here, we review the state-of-the-art in micro-segmented flow as applied in biochemical, cell- and multicellular organisms-based assays. We discuss likely future applications such as single cell / single organism proteomics and transcriptomics and point out the specific advantages and limitations compared to emulsion-based (droplet-based) approaches.