Wouldn't it be nice to have the following features in
      web-interface and API:
      * even distribution of probes by country or continent based on
      population, area, and other user-defined weight numbers;
      * avoiding probes with same ASNs
      ?
I don't know how current algorithm works, but easiest
      modification would be two-step process: (1) randomly select
      country based on specified weights; (2) randomly select probe
      within country, avoiding earlier selected probes or ASNs and
      failing if none are left available; repeat from step 1 until
      necessary number of probes is selected.
    
P.S. I tried to manually request 1 probe from each country, but stumbled on unrecognised country codes, countries with no probes etc. before even trying population-weighted distribution. Without direct access to probes database nice solution can be difficult to achieve via current API, although crude one looks possible.
P.P.S. I understand this option will create more load on probes
      in less-covered countries, but since it's possible to limit
      selection to specific countries anyway this is hardly a strong
      argument against adding this feature.