Evernote is amazing on both my iPhone and my PC. You can create a file for each of your listings and all of your buyers. When on an appointment simply voice record notes and send memos to the appropriate file from your smartphone. Snap a photo and do the same. Watch this video to learn how to save business cards.
The great thing about Evernote is how easy everything syncs. I like being able to send multiple photos and text notes to my PC files from my iPhone. They even give you an email address to forward docs, notes and photos from your email inbox directly into Evernote. You can carry your files with you at all times. The bookmarklet on the toolbar to add web content and PDFs is the best. Did I mention it is free? Real Estate Coach Carol Mazur