Apologies if this topic has been broached on here before (but I can't find a dedicated thread).
I'm sure there must be a whole host of Apple and Android compatible lightmeter apps out there. I have a very nice hand-held meter but it's quite large and I don't always want to carry it with me - but I usually have my iPhone with me at all time (which seems quite ironic as I also often carry a meterless film camera).
Anyway, I was recommended to take a look at "My Lightmeter Pro" which costs about £3 (so not a major cost). It also offers reflective and incident metering (tough there's no "cone" used for incident readings) but the readings were identical to my meter (in daylight, yesterday).
I just wondered what others use - assuming, of course, you don't carry an actual light meter with you.