I've been carrying a small roll of duct tape in both my wallet and laptop bag for years. I've been taking advantage of the fact that duct tape is the same width as a business card. You just roll some fresh duct tape around an old business card ten or twenty times and you'll get a small roll of duct tape that fits right in your wallet.
A year or two ago I found a roll of cloth tape in an ancient first aid kit that we had lying around the house. The first thing I noticed was how similar it is to duct tape. It is fabric reinforced like duct tape, but it is more flexible and less sticky.
It does a great job holding cables together, and it doesn't seem to leave behind the nasty mess duct tape leaves behind when you remove it a few months later. Cloth tape also works great for labeling things; it takes Sharpie ink very well.
The width of cloth tape does not line up as well with a business card as duct tape does. I've come up with a better idea, though. I now wrap three kinds of tape around the length of a business card: duct tape, cloth tape, and electrical tape. The three added together are slightly too big for a business card, so there is a tiny bit of overhang.