I know you can set products to be worth a number of points and do it that way, the points can be added up in a custom entity field.
Tried to find a link @emre sent me but cant find it for the life of me.
EDIT: FOUND IT
You can, haven’t done myself but seen bar-codes used for user login and customer id, barcode readers outputting as keyboard into numberpad you would setup to look for sequence entered, so you would have a ‘customer prefix’ on the barcode number to identify that the following numbers are a customer id. Rules etc to handle the input.
Again struggling to find a link right now as away from desk EDIT: Found something similar - is ticket number barcodes but will get you going in right direction