Pinboard is a service for bookmarking. I heard a lot about it but everytime I thought “Should I sign up?” I decided not to, because I couldn't find a use for it. It all changed when I read Shawn Blanc's Beginner’s Guide to Pinboard 2 weeks ago. I finally found a use for Pinboard, and have been using it heavily since signing up. Like Shawn, I decided to collect everything that is or was interesting to me, every link I clicked, every post I read on Reeder and the tabs I open on my browser. Shawn wrote everything you need to start using Pinboard - Bookmarklets, Apps, Tips and the most important thing - Why to use Pinboard. Signing up to Pinboard costs a one time fee of the number of users * $0.001, so the fee is currently 10.22$. I recommend you read Shawn's guide and sign up for Pinboard as soon as you can, because it's a great service and the earlier you join, the less you'll pay.

Amount by Marco Torretta is a handy unit converter for iPhone. The app is iOS 7 ready and contains units in 25 categories, that you can customize(choose which units/categories to show) like Time, Currency, Weight, Speed and Length. It comes with a history log, so you can see and use previous conversions and also supports basic math actions (and percentages). Federico Viticci wrote a nice review about it that you should check for more information. The app is constantly updated and only costs 0.99$ on the App Store, so even if you won't use it a lot, I suggest you pick it up, It's worth it.

Perfect Weather by Constrast is an app I have been waiting for for a long time. I have been trying a few weather apps, used Check the Weather until I switched to Today Weather. I sticked with Today for a while but it wasn't the app I was looking for, so I when I heard that David Barnard was working on a weather app I was really excited. But, after all the excitement, Perfect Weather ended up disappointing me. Don't get me wrong, the app is really great and it has exactly the features I want from a weather app, but the app only works in the US, so it useless for me. Dave Caolo of TUAW prepared a nice review of it, so if you are in the US and looking for a great weather app, check Dave's review and get Perfect Weather - it's only 2.99$ on the App Store.