Stuart Jeffries considers the exclamation mark:
Carol Waseleski's unexpectedly diverting paper, Gender and the Use of Exclamation Points in Computer-Mediated Communication, found that women used more exclamation marks than men. But why was this?…[Waseleski] concluded that exclamation marks were not just marks of excitability but of friendliness, and suggested that one reason women use them more than men is because they were, as a gender, less likely to be socially inept, funless egotists …
Ha!!