In this paper, we focus on how vertical-cavity surface- emitting lasers (VCSELs) and arrays have led to many feasible advanced technological applications. Their intrinsic characteristics, performance, and producibility offer substantial advantages over alternative sources. Demonstrated performance of `commercial-grade' VCSELs include low operating powers (< 2 V, mAs), high speeds (3 dB BWs > 15 GHz), and high temperature operating ranges (10 K to 400 K and -55 degree(s)C to 125 degree(s)C, and T > 200 degree(s)C). Moreover, their robustness is manifest by high reliability in excess of 107 hours mean time between failures at room temperature and tenfold improvement over existing rad-hard LEDs. Hence, even these `commercial-grade' VCSELs offer potential within cryogenic and avionics/military or space environments. We have also demonstrated submilliamp ITH, stable, single-mode VCSELs utilized within bias-free 1-Gbit/s data links. These low- power VCSELs may also serve in applications from printers to low-cost atomic clocks. The greatest near-term VCSEL applications are upgrades to low-cost LEDs and high-grade copper wire in data links and sensors. Exploiting their surface-emitting geometry, VCSELs are also compatible with established multichip module packaging. Hence VCSELs and VCSEL arrays are ideal components for interconnect-intensive processing applications between and within computing systems.