Sure - and let me know if you want more than this.
Owntracks will monitor your location every X seconds. You can also give the app key regions (Ive added all of my Wife's office locations, main training sites etc). Each time she arrives at a region, or the location changes, (and then remains unchanged for a period) I run a GET google maps API query, for journey time/route home. A piston then uses this to calculate an early time (unless location changes) to rerun the query for a live journey time (which is usally more with rush hour traffic, hence running it early) and it messages her with the info. If she doesnt leave, it messages again, more urgently (which she uses to excuse herself - 'I have to go, see'). For certain offices, with really bad traffic issues, The piston runs the query periodically, watching for 'and they shut the tunnel...' that wouldnt be caught in time if left to expected journey time.
The win is the reminder of journey time based on current location. She is an optimist, and thinks everywhere is 20 minutes. 
