Making and sharing game maps online?

[PalladiumBrony]

Any good resources for making maps online? Both on the "macro" scale to keep track of where in the world the party members are, and on the micro scale for playing specific encounters? Does anyone have experience with virtual tabletops in general - dice rolling, character movement etc. My ideal scenario would be to have a virtual map on which all the players could move their character markers/tokens, and the GM could move NPC markers, and also see things that weren't necessarily automatically obvious to players - such as the location of traps or hidden doors - but could reveal them to the players once they've gone through and found them - either the easy way or the hard way!

What kind of rules of thumb do you use when figuring out the size of a map - like, say your Palladium Fantasy party descends into a cave to do a little exploring, or your Dead Reign party is exploring an abandoned hospital, how big would be too big/too small? It does get more complicated when you consider that movement isn't conveniently measured in "squares" of uniform size, like in certain other RPGs. I suspect for example it would probably be boring to have to spend 10 turns in a row just traversing a straight hallway, especially if it didn't have anything cool like loot or a trap in it.

[Crimson Dynamo]

Inkarnate has been the one I've been using for a while for my D&D campaigns. It's really focused on medieval settings if you try to build local maps, but you can make beautiful geographical maps just fine with it.

Here's a quick map I made for a one-shot adventure a few months ago, as an example. It's pretty awful conceptually, but it does show some of the stuff you can do with it.