Not sure about NavPanel (it's already too cluttered), but would be nice as an info-panel popup in the System Map.
Or, as has been posited before, Explorers could drop an Exploration Beacon and when you scan it you get the list of Commanders that have scanned it before you, as well as adding your own name to it.
Either approach would require Server Infrastructure and additional network traffic though, so might not really be feasible to scale up.
EDSM unfortunately just tracks summary visitor numbers and ship types, not names. Apart from the obvious privacy issue (for a third-party site), which could, of course, be opt-in, it would also require additional server support to have a full visitors list. Still, I think it'd be nice too.