I wear 36 inseam pants, they're not too hard to find usually:
American Eagle, GAP, and Eddie Bauer all have good selections of pants with 36 inseams. I like AE pants for casual, GAP for casual/work, and Eddie Bauer for work/dress pants. JCPenney has some pants with a 36 inseam, but pretty much the only kind of khakis they carry are pleated, which is why I go to Eddie Bauer usually.
I've never seen 36 inseam pants at AE or the Gap (and only a few at JC Penney) in store, so I usually have to buy them online. It's kind of a trial and error proceedure, so make sure there's a local store to you to make returns easier.