"Waifu Collection" is a free app for Android and iPhone. The user collects virtual cards, each one featuring a particular character and her seiyuu.
The "card" includes a set of voice clips, as well as other functions: the user can stroke the character's hair, or kiss the character -- virtually, of course -- and the character will respond in some way. Like a simplified version of what happens with the Love Plus game.
The most recent card is for Yuuki Aoi's Giselle, in Last Exile: Ginyaku no Fam. There is already a card for Fam (Toyosaki Aki): (click image to enlarge)
Here is the website, where there are links to the Android Market and to the iPhone App Store.
In Japanese, the app is called 嫁コレ Yome Kore, "bride collect(ion)." In Japanese, the otaku cry "...is my waifu" is ...ore no yome ("...is my bride").
Another function of the cards is being able to insert the character into any photos the user takes with their phone, like this: