I used to think that bus-spotting was rather a.....'special interest' hobby...
Then I found out that there is actually a group which considers spotting manhole covers and drains to be interesting. I kid you not. Well, I suppose it takes all sorts, but drainspotting ???
But how about
The Pylon Appreciation Society. A quote from the website "the Pylon Appreciation Society is a club for people who appreciate electricity pylons." Takes all sorts, I suppose...