From Ajax Patterns
Might this be better termed, "Incremental Registration"? It's not really "lazy" in the sense it's usually used...which is deferring doing something until it's necessary. This pattern does defer formal registration, but the essence of it is that it incrementally collects information that is then applied to that formal registration. You can defer registration without that incremental collection, and many sites have done so for years and can be called "lazy" about doing it, but those sites are not implementing this specific pattern. (-peeder)
Peeder, I added Incremental as a tag/keyword. I decided to leave it as Lazy for now because I feel that the pattern lets the *user* be lazy about registering, in the comp sci sense of "lazy" vs "eager".