Font rendering: I realize jMockups might only render "web-safe" fonts. But I would love to see an iteration that incorporates any typeface shared between a team of designers who have fonts locally stored. I have made attempts to switch to Inkscape, but it's inability to render different type formats is what is holding me back from using it.

Drawing path tools: This would be handy if I needed to create arrows and icons. I suppose I could draw them and import them as images; however, it would be really nice if I can draw them in directly!