This is the popular way to design tech nowadays a far as I can tell
Today's free design resource DO App UI Kit is designed and released as a freebie by Invisionapp.With this app UI kit you can build all kinds of apps.DO app UI
Tourism icons - design by Yoon J, via Behance
Flat Design APP UI Components based on iOS 7 visual guidelines. All elements are completely editable vector shapes, included in a single, well organized PSD file. you can use the ui pack for your App and Web design.