Mobile bar code scanning app Red Laser has reached the elusive feat of being among the iPhone’s top five paid apps for three consecutive months (via MobileCrunch). Oh yeah, and the $1.99 app has brought in $1 million in subscription revenues.

This tells us a few things. 1. It’s still possible to have an app succeed among the 100,000 in the App Store, based solely on its quality: The company has done zero marketing. 2. As we’ve written, bar code scanning technology will be hot.

To the second point, visual search generally will be one of the more interesting areas of mobile product development (same goes for alternate search inputs like voice). This includes augmented reality in the future, though comprehensive data will be a gating factor (see our writeup).

But for now, visual search is happening in a practical sense with bar code scanners. Red Laser’s subscription revenues are one proof point. Ad revenues will also come into play, given the value and buying intent of individuals who are at the point of purchase — literally standing at the store shelf.

The true value will be unlocked when there is more content in these product databases that tell users where to get scanned products at nearby competing stores. Similar app ShopSavvy already does this with local inventory data provider Krillion.

ShopSavvy also has an interesting way of looking at bar code scanning, treating each scan almost like a search query. Its model will involve creating a bid marketplace where advertisers buy scans the same way they currently buy keywords on Google.

That’s even more reason to think of bar code scanning as just another form of search … it’s just using the phone’s camera instead of the keypad. This is a product model that wouldn’t make a lot of sense on the PC but is quite fitting to the mobile device “form factor.”

The previous sentence is generally my litmus test for handicapping mobile apps in 2010.