E61i + Krusell Classic case = :-D
Interestingly enough, the Krusell Classic case seems to improve E61i usability since it makes the phone much less slippery and provides more tactile feedback when using the keyboard. And, of course, the case also provides protection from scratches.
And since Krusell Classic cases include a spring clip, there's no need for a separate holster.
The E61i has become quickly become one of my favorite Nokia devices and Krusell Classic seems the perfect case for it.