Well as someone who is having trouble keeping motivated when running I thought what i needed was a running partner.  After trawling round the web where I found little helpful I came up with the idea of a nationwide web site where the end user posts by geographical location and then by activity for a sport buddy.  Perhaps there could also be a level of competence for that particular event so people can see the ability of the other.  Like all social web sites it depends on how many people use it but personally as someone in the same predicament it would be incredibly useful!