Persistent website registerer?

Hi

I run my own site and have noticed in the past fortnight that an anonymous person keeps registering new ID's at the rate of 2 each day.

The IP addresses were initially so similar that I knew it was the same person- now slightly differing, plus they create similarly long and weird user-ID's and always use Gmail.

This person isn't as yet a troll (I haven't even activated any of his/her ID's) but it's a PITA checking my emails only to see ...yet another 'ID' wanting activation!

I don't want to stop registrations per se as everyone would be affected. It's the bloody irritation factor!

What would you do?

Hi

The IP's are now changing constantly, though someone else suggested it may be auto-generated 'Spambots'. Harmless but annoying.