As an example to the potential of on-going AGN surveys we show how to select a set of radio sources with a structure-related objective: e.g. to study the size and properties of the narrow-line emission region (NLR) in AGN. A straight radio jet blasting through the NLR/ISM border suffers shocks that are seen as prominent radio features. From a complete sample of 1665 radio sources, we selected, by size alone, 55 objects with features on 0.1-1 kpc scales (and flux ratio > 7:1 as compared to the core) and are studying them in detail at optical and high resolution radio. In addition to explaining the radio interferometric selection technique that we used, we will also speculate on the prospects for size selection of sub-samples from other wavelengths/surveys.