Whenever I think about designing seemingly simple features, I reflect back on this to remind myself how nothing is as simple as it seems: For Exchange 2000 Service Pack 2, I was tasked with speccing out a feature - type-down search. In Outlook and Windows Explorer, this is the feature whereby you can sort on a column and then start typing, and Outlook/Explorer will automatically scroll down and auto-select the first item that matches the characters you type.
We brainstormed the ways this could be implemented, came up with a few, and narrowed it down to two:
So we spun off efforts to investigate the performance & international side of things, and set about doing usability studies for both methods. We weren't sure how users would react: on the one hand, with method #1, there's no indication to the user that type-down search exists - would users think to try it? With method #2, there's an indication to the user about what to do once the user sorts on a column, but it adds a step to the process of sorting by a column, which could be annoying.