Build an addition onto the house.
Seriously, we have made our bedroom into our ultimate sexual area. We have over 300 toys, 300+ DVD's,(porn, original cases), 275 DVD's of clips from Videobox, and I have over 50 pieces of lingerie. AND...we still need more!!
I have been creative and we have amazing storage options for our current items with much, much more room for more. We stacked 2 matching antique dressers, the 10 drawer on the bottom and the 6 drawer on the top. This only took up 2'x8' of floorspace. I have a bookcase with doors, 18"x4' floorspace. And for other adult item storage, I have 3 antique steamer trunks for the little nooks. I could NEVER have too many toys!! Oh, broken or hateful toys go under the bed in rubber maid containers for toy repair or to experiment on other options.
Oh, seriously we also have 2 pretty much empty spare bedrooms now that our kids are adults and on their own.