Lately, I've had to do some editing of images to produce icon buttons for databases we subscribe to. I wanted something quick. Rather than fire up Photoshop, I've been using Pixlr.
This easy to use, web-based app loads up quickly into your browser. While the Advanced version (one of the choices) gives you layers and Photoshop-like features, "Pixlr Express" is quick, did most of what I wanted to do, (text, borders, stamps, cropping, etc.) and didn't overwhelm me with options. The Pixlr-o-matic (also available in an iOs and Android app) is very simple - allowing some borders, overlays and filters for a quick effects wash. Give it a try.