Show when the information for each lead was last updated.
Obviously, it's impossible to have the best info on everything all the time. That being said, it would be very nice to know when the information was last updated. If a record hasn't been updated in 2-3 years, it would be nice knowing that the info might not be 100% accurate (as compared to info a couple of months old). It wouldn't have to be anything crazy detailed, just something as simple as "2+ years ago" "1 year ago" "few months ago" etc