I've long thought that it would be great to replace all kinds of signage wit eInk. Time tables on public transport, any kind of announcement that's typically printed on paper,... There's lots of stuff with a low refresh rate (sometimes in the order of months) that could benefit from being easier to update, but that isn't worth replacing by power hungry, overly bright, hard to read LCDs. Hell, there are a lot of cases where LCDs are used wher eInk would be a much better fit. Things like meeting room reservation screens, for instance.

With largeish colour displays, maybe that'll all finally become a reality.