I am in love with this little pouch I bought from Gap. It's currently on sale for $9.
I haven't used it yet but I plan on breaking it in for my trip to Houston. It's got a "wear me" side and a "wash me" side so I'll pack all my clean underpants on the "wear" side and the rest is obvious. What a cute way to keep things tidy, wouldn't you agree? I feel like you could easily make a pouch like this too. Perhaps there's a DIY coming in the future.