I use Microsoft Outlook to manage most of my work life. Since I get a ton of email, I have a rigorous discipline for staying organized - try not to read any email more than once, keep my Inbox down to a manageable number of items, move things to my task list if I have to follow up at a future date, etc. Most importantly, I have a filing system so that every email worth saving is put into a folder to save in case I need to look at it in the future. I've got customer folders, department folders, project folders. I've got folders of folders. I've got so many folders that I can't find anything. Yikes, maybe my system isn't so good.
When I really need to find something that I've filed away, I used to use Outlook's built in Advanced Find tool, seen below.
This should be Exhibit 1 for the case of how to design a bad user interface. I'm not a big Microsoft basher since I have a pretty good appreciation for how hard it is to develop good sofware. But this User Interface sucks. And to make matters worse, this is not even the biggest problem. I have a ton of saved things and the Advanced Find takes forever to run (well technically not forever but anything more than 30 seconds is forever in my view of computer response time). If Google can index the entire Web and have a search result in subsecond response time, then perhaps Microsoft picked the wrong search algorithm.
So last month I started using a new Outlook add-in called XOBNI (Inbox spelled backwards, pronounced ZOB-KNEE).
Now this is what a good interface should be. This bar sits on the right of your Outlook window and can be collapsed away easily if you don't want to look at it. Just type it in the top search bar and a few seconds later any emails that are stored in any folder that contain what you're searching on are returned. Xobni doesn't index your deleted items which is a small gripe that they say will be addressed in the future.
There are a bunch of other features that might be good if I could get in the habit of using them but the search alone makes it invaluable.
Best news of all - it's free. I'm not exactly sure what their business model is - maybe it's just get everybody using their tool and sell to Microsoft. Well that's OK with me since they're saving me a bunch of time.
If you use Outlook, this is a no brainer add-in.