Control over axes ranges
Allow setting of the min and max value displayed on a visual's axes
Customize the formatting of numbers
You should be able to control the formatting of numbers in tiles on the dashboard and in reports. For example a tile that shows "0.1M" might be better with a more precise number like "123,456".
Radial gauges
Add gauge visuals to show progress toward a target. Some inspirations: http://www.bing.com/images/search?q=dashboard%20gauge&qs=n&form=QBIR&pq=dashboard%20gauge&sc=8-14&sp=-1&sk=
Embed visualizations in an external webpage
Let me embed PowerView reports and dashboard visuals in another webpage.
Enlarge or Expand a Visualization to fill canvas.
Unable to enlarge or expand a visualization to cover the full canvas. This feature was in the Power View add-on for Excel and would be useful in the dashboard.
Add PowerPivot Models to Power BI Designer
At the moment with the preview version of Power BI Designer PowerPivot models not available. It would be great if we could load tables from Power Query into PowerPivot. It's just available in normal Power Query but not in Power BI Designer tool.
Control whether a visual slices or highlights other visual
Rather than cross-highlighting when you click on a datapoint, give us the option to have it filter other visuals!
Certificate Authentication on Mobile iOS app
Enable Certificate authentication on the iOS PowerBI app.
Library of Crowd-Sourced Visuals
There should be a place where power-users can upload all the custom visuals they are developing. This should be a public forum for everyone to browse for the newest, hottest visuals.