This one, in fact: Yarn U
I have an awful lot of knitting related apps on my iPod. A. Lot. And of those, guess how many I actually use? Maybe one, when I remember to.
But I think this one might actually be useful. I can’t tell you how many times I’ve been in a yarn store, and after 4 years of being an active knitter, am still too dumb to read and understand a ball band (If you can actually understand how a ball band relates to real life, please give me a holler!). If it doesn’t specifically say, “this yarn is this weight, and it will look like this when you’re done with it, and it will be splitty so please be careful,” then I’m pretty much out.
Yarn U is a collection of descriptions and pictures for over 100 different yarns. It gives basic information, honest reviews, and great pictures. This is one that I will pull out in the yarn store when I’m yarn shopping, and don’t want to run home to search Ravelry before I make a decision (um, like you haven’t done it!). Hopefully, more yarns will be added as the app is updated, because there are still a few other yarns I would like to see. But I am very excited about this app, and sincerely recommend it to all of my yarnie readers!
(Side Note: Fabric U, its companion app for sewers, is also fantastic!)