OK, I may be pilloried for admitting this, but I don't always have homemade stock in my freezer, and when I don't, I use canned stock!!
Tonight I made Mark Bittman's Risotto without stock:
It turned out really well, the dried porcini and onions kind of makes a stock before you begin adding the water. I did use white wine, added baby spinach when it was almost done, and used a really good parmesan.
Anyone else tried this?