Ooh, a chance to plug a toy side-project! I wrote "pingd" [1] to ping an address continuously and dump (timestamp, latency, dropped) tuples to a SQLite database, and also report results (tables only, no plots) via a web interface. Slightly less hacky than "ping host > logfile". Also to shame Comcast.

[1] https://github.com/cfallin/pingd (in Rust, requires liboping)