Yes, OK barcodes are a hobby, but I have been looking at the different apps you can get on an iPhone. I imagine many are available for Android as well.
Firstly, I have to say this: Why the hell is reading barcodes not STANDARD in the camera function in the phone?
After all, it has face recognition - why not put a box around barcodes it sees and you poke the box and it reads the barcode and does something with it if it knows what it is. Why on earth does a phone like an iPhone need an "app" to read barcodes in the first place. Crazy. I can see merit in apps being able to hook in to that, registering URL schemes and so on to handle the barcodes you scan and do specific things, but why an app to read the barcodes in the first place. And then there are a million (exaggeration) different apps to choose - how does a user know which app to use?
i-nigma is an app that has been around for a long time, it is free, and it will read IEC16022 and IEC18004 (data matrix and QR) 2D codes as well as 1D barcodes of various sorts. If the content looks like a URL it opens that in a browser, or will link to things that register a URL scheme like otpauth for one time passwords, etc. It is quick and seems to work well. However, it seems to use a low resolution on the camera meaning it cannot read high density codes, and has its own decode logic which means it cannot handle some high end UTF-8 QR codes (e.g. pile of poo).
QR Reader for iPhone
However, the biggest feature of this is that you can tell it to feed the codes it reads in to a web site of your choice as an argument and display the page it gets. This means it can work as a front end for your own web based applications directly.
Seriously - that is awesome - I don't need to make a mobile app to do stuff with barcodes, I can just do something on my own web site. I am now thinking of all the things we can do with this, and we'll never have to buy a bar code reader again. At work we scan serial number of routers, for example, but we can do way more than just type in to the keyboard now, and we can handle 2D barcodes as well (we only have 1D scanners at present).
Most other readers
I have tried several others. Some are not free (ha!). Some will not read IEC16022 codes (Datamatrix). Some only do 1D barcodes. Some are packed with adverts. Most do try to link in to selling you the thing you have scanned in some way. But so far I have not found one as good as the QR Reader app.
If anyone knows any that are better, let me know...