The posibilities are endless with that domain. It is also an activity where a lot of disposible income can be used up. I know people who have spent nearly $18K on a xxxx.
The only time I have ever spent anything more than the registration fee on a domain was to buy back a domain I had let lapse because I wasn't using it. I had watched the domain for a number of years after I had let it go and it was just parked. The squatter was asking $40K for it which was way to steep for me.
However one night I was watching Dragons Den and someone was pitching an internet related idea which looked to be going well. Until the question "Do you have the dot com ?", and when the answer came back "No" all the dragons chorused "I'm out". It was at that point I realised I had better get the domain back if I ever wanted to sell my business in the future.
I managed to get it back for $6K, not bad considering the $40K price tag, but still a pretty expensive mistake to make. And I still haven't done anything with the domain and have just parked it. One of these days I will get round to developing it.
Most expensive parking ticket I have ever bought !