I'd upload some Bitcoin to an Instawllet and send them the link.
As you say, that way you can reclaim it if they never take it. I don't like the idea of the recipient only having 14 days to claim bitcoinmail, but then, the service is free so they need to pay for hosting somehow.
The 14 day claim period is a huge stumbling block. The last thing I would want to have happen is not being able to get the funds back in the even that the person was somehow *not* able to claim the funds. Basically this puts the risk exposure to me somewhere around the $20 mark for using that service.
For example, I just made an auction purchase for $785, there is no way I would ever send that via a service that could claim the coins after 14 days if for some reason the recipient didn't receive the e-mail, etc.
The site (that I'm proposing) really needs to define itself as the payment escrow/caretaker for those that don't have the knowledge/resources to conduct the transaction directly with the current Bitcoin clients. Piggybacking on a current exchange/online wallet service that can ACH transfer funds directly to a bank account would obviously be of great use as well and rapidly spur adoption. Essentially it's all the familiarity of using a site like Paypal, except instead of $ it's BTC.
How you would monetize the service to pay for hosting, etc - I'm not 100% positive. However the startup cost for developing/hosting such a thing is so nominal these days that I would rather focus on something that services the community first, figures out how to build a business around it later.
Again - if someone is serious about attacking this - I'm happy to discuss in more detail.