The wonderful Mr. Howard is having a contest over on his blog in correlation with Fishing our way across Colorado 50 days 2 writers. For the contest, you must post about what kind of fishing app you would create for an iPod/iPad.
Before we get started, I will say that I do not own an iPod and I've used iPad and wouldn't waste my money. But to each his own.
For the app...... I would design a Hatch Matcher. Actually, you would need two versions. With the earlier generation of iPad/iPods you would have an app that contains a database of images of insects in all stages of life. You could then compare an insect that you found streamside with one in the database to get a match. There would also be suggestions on what fly to use to match it.
But, for the later generations of the iPod/iPad's that contain a camera, you could take a picture of the bug and, using image recognition technology, the machine would be able to detect traits and chose which insect (or insects) that closely resemble the one that you took a picture of. And it would have the fly suggestions.