[1] Modern air warfare still uses a form of blip enhancement to present false targets, through both passive retroreflectors and active amplifying retransmitters.
The early ADM-20 Quail uses a passive corner reflector design to present an RCS similar to the Boeing B-52 Stratofortress.
[2] The later ADM-160 MALD only uses a multi-band active system called signature augmentation subsystem, which allows emulating any desired RCS in a range.
Small watercraft commonly use a passive radar reflector to make them more visible, but active retransmitters/transponders are also commercially available.
[7] For small aircraft use, a 1975 US DOT report concludes that passive reflectors provide insufficient enhancement and that contemporary active retransmitters are too likely to interfere with ground radars.