More keyboard shortcuts, esp. for resizing...
You're no doubt familiar with Balsamiq Mockups — it's like a tiny itty-bitty baby version of Justinmind. I used it for years before realizing that we needed richer interactions in our wireframes.
One of its great features is that once a component is selected, in addition to moving it in 1- or 10-pixel increments (actually, in Balsamiq, 20-pixel for some odd reason), you can also resize the selected element by holding down a different modifier key and pressing down or right. It's very handy.