Are business cards genealogy documents in disguise? They can be. I know when a family member died a few years back, his collection of business cards led me to relatives and their phone numbers. They also served as a timeline for his own life and where he worked over the years.
Consider this business card I picked up at a vintage paper fair this year.
Not only is the man's name, address, phone number and occupation listed but at the top right he provides the names of his three daughters. While men's business cards are not typically seen as a source for female ancestors, in this case it is.
Business cards can carry important information While there isn't many places to find them currently, be on the lookout for business cards as home sources in the homes of other family members.