This is something that's bugged me for awhile, and I kind of hoped it'd be fixed in v7. In the search page, the default option is for posts newer than 1 week.
Now, for really busy sites, this is probably good as it saves on server resources. However, my site isn't all that busy... and... well... some of my users aren't exactly the brightest crayons in the box. Searching in general typically eludes them, and if they do somehow manage to accidentally find the search page, it has a tendency to return zero results because they didn't see and/or realize the importance of the date limit. No results newer than 1 week obviously means the question has never been asked before (*cough*), so let's ask it again. You see my dilemna.
It's super easy to go in and just change the code to default to another option. But changing the code means it'll probably get overwritten when an update is released. Maybe not every time - probably not every time. But an admin option to set the default search date limit would be really nice. So busy sites can leave it as 1 week, slower sites can change it to 6 months or so, and no code changing is necessary.
Just a wishlist thing. It's really little and nitpicky, so I don't expect it to rush to the top of the whiteboard or anything. But if you're ever bored and wanna add a new setting to the control panel... it'd be nice.