Well, I don't have a particular niche so to speak. I just go for domains that I think represent good value / business prop and / or something I feel comfortable to get into. I like new things
I have a few projects going on at the moment, but in terms of domain buying / drops... recent purchases are:
daewoo.com.au <- developed (not completely finished, but you get the picture)
cheapprintercartridges.com.au <- to be developed
greencoffee.com.au <- picked up to distribute product from official US pharmacy manufacturer, parents are in the coffee business and wanted me to help them