Rest in peace!
Edit: All these (great and much appreciated!) responses of alternatives are making me wonder if this should in fact be a standardized service that could then be offered as a public good in a similar way as pool.ntp.org.
Checking for generic Internet connectivity (i.e. not only having an IP address, but being able to reach public sites, these sites being non-cached, not-captive-portaled etc.) seems like a problem that too many apps, scripts, and devices are solving again and again.