Full Screen Caller ID Free for Android lives up to its name with big, bright contact cards, but it goes a little overboard with ads. Of course, there's a paid version that gets rid of those and unlocks some extra features. You can change so many things about the free version, though, that you might not ever need to pay.
Full Screen Caller ID Free for Android fills your entire screen with a picture of your contact whenever they call. Interestingly, it makes the contact card appear whenever they text you, too. This gets a little annoying if you're going back and forth with the same person. Luckily, you can hide any notification with an easy double tap. The app lets you ignore any message and send a "call back later" text with the touch of a button. Just like most of the app's presentation, you can change what that text says from the app's settings menu. You can upgrade to the full version of the app from the same menu. For $5 you can unlock a few extra features and eliminate the program's ads. Since ads hit you in every part of the app--including your contact cards--that might be a worthwhile investment. Either way, the app is a neat way to view your contacts and a welcome change to Android's default caller ID.
It's a saving grace that this app is really customizable and lets you tweak just about any element you want. You might forgive the ads for what you get in return. If not, it's a fairly small price to pay to get rid of them.