I know that some of the below suggestions have already been made, but i ask that you bear with me on this list.
1. Have an option to make resizing a fence snap to icon-width or icon-height as a unit of measure, including the padding when it is beyond 1. It is very nice that we can make the fence exactly 1 icon wide or tall but it is a pain for larger dimensions to get it the minimum size without scroll bars, especially when it snaps to nearby fences, though that is useful for setting up multiple fences of the same size.
2. A global option to change or disable fence snapping on the desktop in terms of location. I have a set of fences that is 1 icon and 4 icons tall next to a set that is 3 and 2 (each group of fences is stacked on top of each other with identical minimal spacing between them) The problem that i have is that the 4 icon's tall group is longer than the 3/2 because of the padding between the icons and i want to keep the same spacing between my fences.
2b. Another option that might go with this is to have a 'bubble' around each fence that the other fences will snap to first so that you can specify the distance between each fence.
2c. As mentioned earlier, snapping to edges of the desktop, screen, and start bar would be nice.
3. As someone stated before, have an option to allow a fence to resize automatically to avoid the use of scroll bars.
4. have an option to allow Win-D to unhide the fences, but also allow that to be disabled for those of us who also like to periodically look at our pretty desktops while working
5. As mentioned before as well, have an option to force the label of a fence to appear on a certain side, including forcing it to stay at the top even if the label is moved beyond the boundaries of the screen.
6. As mentioned before, have an option (probably Pro only) to have an 'effect' added to an icon on mouseover, such as a growth, with or without nearby icons shrinking/moving, or some kind of glow, or maybe a glass shine, or sparkling for the ladies, etc.
7. Though i try to avoid them, the suggestion of having horizontal scroll bars is a nice one, and i would go as far as saying that it would be nice to choose which side they are on to the point of vertical on the left or horizontal on top or bottom, not just the current right oriented version.
8. Though it is probably a rather useless idea, have a per fence option to disable the automatic shuffling of the icons where i can specify an external size (ie, the size of the fence on the desk) and an internal size (the amount of space available to the icons within that fence, active with scroll bars) and allow the internal to be no smaller than the external and allow the standard windows desktop options of snap to grid or free move for the icons so that they can be arranged into nice patterns. This would be an option that would be set to auto by default and available in an advanced options section of an individual fence.
9. Not a new feature but more a change in the defaults, have fences take a fence snapshot before changing resolution (as some full-screen games are wont to do) and restore the fences to that snapshot when the resolution reverts. This would solve some of the drifting problems that i have noticed when running older games on very small resolutions so that there is different spacing of the fences than when i set them up. If a new fence is created during the lower/higher resolution period, have that move as it normally would with a resize.
That is all that I can think of for now, if any of these ideas needs clarification, please ask and I will try to be more clear. Thanks for the awesome software that has freed my desktop from Microsoft's stupid vertical only icon placement.