Truth be told probably the camera (for anything, cards, notes, sales coupons, receipts, even credit cards i forgot, etc)
Now for specific Apps to say get a format like pdf, etc. There are numerous, I like an oldie but goodie Google drive (both on iDevices and Androids), now I have to trust that my data is safe, but truth be told I do need my info to be in the cloud so i can access it elsewhere later