If you're adding more verticals to a parent product, make sure the verticals you add are closely linked in the mind of consumers, and not just in the data that defines them.<p>We've seen both sides of this at HotPads. The site started out with rental housing only and added for-sale listings a bit later. Those two verticals are closely linked and we made a 'buy vs. rent' search to tie them together. The addition of the real estate vertical worked out very well.<p>Last year we added hotel and vacation rental listings. Aside from tighter scheduling rules, the data behind these listings is very close to apartments, but nobody thinks about finding a place to stay the same way they think about finding a place to live, so getting users for those verticals has been much more of a struggle.
The bigger question is how you decide which vertical to go after, and if it is a big enough opportunity.<p>Ideally, you want to address the biggest market possible, but you can't do that and have passionate early adopters at the same time. No having your cake and eating it too. Picking the right vertical and sticking to it in the beginning requires a fair bit of effort.