Since I started collecting the Executioners, I've acquired 2 Land Speeder Storms. I hadn't really intended to use too many Scouts with the Executioners until the current codex, but both of these Storms were really good deals from players that had started Space Marine armies but decided not to finish. It was just one of those cases where I couldn't pass up the deal.
This is Dagon's Teeth, my first Storm.
This model was assembled before I got it, so I just swapped the weapon out for a heavy flamer. In this case, it's a normal Land Speeder multi-melta with the barrel replaced by a heavy flamer barrel, I think from a Baal Predator sponson.
I'm really looking forward to playing with the Storms, as the combination of the substantial firepower with a very mobile Scout squad sounds like a lot of fun. Next, I'll be painting the other Storm, which is the last model that I bought for the Executioners that isn't painted. After that, I'll have to buy some Scouts to actually ride in them. The only Scout squad I own is a sniper squad, and I don't think that would work very well.