Display number of days a member has been a member
 

A member asked me if there was a way to display number of days a person has been a member, like underneath the 'member since' date. For example, currently in postbit it says something like

Member since: March 28, 2007

and she would want to add under that

Member for: 30 days

And of course for each additional day someone is a member, it would add another day. It would be even better if there could be a choice to have a day/month/year thing, so after 30 days it converts to one month, then 12 months converts to a year, etc. like

Member for: 1 year, 3 months and 24 days

Is there a way to put code in to show that, that wouldnt overload the server too much with the daily update?