I have all my clients get on myfitnesspal or mynetdiary. Both can be used for free online or via mobile app. Clients can scan barcodes with their smartphones.
The downside I am noticing is that clients are using entries that other people have databased. The tendency is for the total calories to be correct but the breakdown of macronutrients is worthless.
I am currently encouraging clients to database their own foods so that the nutrition information is complete.