It is the simple things that are often the most useful. One of the accounting staff where I used to work used to spend about 2 hours each day manually comparing two data dumps (one from the accounting system and one from the bank) to make sure all the transactions matched up. They would print out both reports and use a ruler to match up lines.

It took me about 2 hours to write a little webapp where the two files could be uploaded, and it would spit out a report of all the ambiguities in about a second.

It amazes me that every worker these days has a computer on their desk, but the majority still don't have a clue what computers are really good at. They are used for writing memos and playing solitaire!