I was just talking with Betty at Larry's about how it would be nice if they had links on the website to the Briess data sheets, and the Wyeast product info, etc, so that it would be easier to reformulate a recipe that calls for a brand that they don't carry.
I always sit down with about four browser windows open, as I am going over a recipe from a book or BYO, or on here, etc. One is to Larry's site, so I can double check their products, one is to Briess, so that I can get to the data sheets on their malts and extracts. One is to White Labs, so that I can find out about a specific yeast, and one is to Wyeast, so that I can come up with an appropriate replacement, if the recipe called for a White Labs yeast.
I think I remember someone saying that Mr. Malty has a pretty good yeast comparison, but I have not checked that out yet.