Not really sure where to put this.
We've tried to to migrate part of our Pathfinder sessions to skype. Everything works pretty well using only free resources but something we're in dire need of is some way to handle hex map exploration online.
It needs to allow us to arbitrarily number the hexes, to color them and to draw things on them.
You can use hex grids on roll20.net.
You can. The only issue is that it's -- literally -- more cumbersome to do that than it is to re-draw the maps by hand. Roll20.net's hex map processing facilities are terribly inconvenient.
I tried using roll20.net for exactly this purpose. The experiment lasted less than an hour, and then I decided to pull out my old hex battlemat and a set of wet-erase markers.
Yeah, roll20.net handles Kingmaker well. I've ran a kingdom campaign in the past with no issue.
Edit: Huh, that's odd. I never had any of the problems Orfamay describe. I uploaded the country map, changed the grid to hexes rather than squares, and used simple icons to show hex improvement - pickaxe for mine, grain bushel for farms and so on.
Once I had the illustrations needed it took about five minutes to set up.
I've been using Roll20 to play out Kingmaker for a while now, and so far it hasn't been giving me too much in the way of grief - not only can you import the Stolen Lands maps pretty easily (sizing them can be a bit finicky, but once you get the hand of it the process is fairly painless), but you can also use hex tiles from the marketplace or free resources if you want something a bit more 'personal'.
A good trick is to set all of the icons like gold bars or forts (and possibly the corresponding map letters) on the GM layer, and once the hex is explored you can just swap it into the token layer when they discover it.
For later on when they get to making their kingdom, it's also pretty easy to make outlines with the line tool and whatnot.
Conversely, there's Hexographer, but that probably won't work too well to meet your needs.
Edit: One thing needs to be said about the drawing tool and that there is no 'erase' tool unfortunately. When you finish drawing up a line or a shape it becomes it's own object that you can scale and move and stuff, but the only way to take out a little bit is to remove the whole object and start again.
Also someone will draw a phallus on the map within the first two minutes.
I threw together a quick example of how I set up the kingdom campaign on Roll20 - I didn't bother setting the perfect resolution etc so the icons are a little blurry, but you get the idea. This took me about 5 minutes, most of which was fiddling to make the grid lines match up. Like Pigtails mentioned the drawing tools are not perfect, so you may be better off imposing your own illustrations on top of the map rather than using the drawing tools unless whatever you're sketching is meant to be temporary. If you do want to draw something that'll most likely be changed rarely (like kingdom borders) then you can draw it directly on the map layer.
We just ran a quick trial just me and the GM. Some issues we noted.
It seems that only the GM has control over the layers. So regular players can only draw on some "default" layer.
The GM had severe trouble aligning the two hex grids together.
The players can only draw on the "token" layer, while the GM can draw on all layers.
Aligning the hex grids is tricky at first but becomes easy with practice - count the horizontal and vertical hexes, then right-click the map and input that as the size and it'll resize it for you. Alternately just turn off the grid, it works just as well gridless.