I'm getting bored of the resources so far. I guess for a couple of reasons. There aren't all that many, so I feel like they're kinda spammed everywhere, making the map feel crowded and not very interesting. The objective of this thread is to give a greater variety of resources without really adding anything excessively complicated.
Idea #1: Resource Synergy
Resources are divided into groups based on what they produce. That is: Food Producing Resources, Economic Resources, and Material Resources. Other resources that produce research, horses, ore, or spell points are unaffected.
Food Resources (wheat, apiaries, orchards, and fertile ground) will essentially all produce the same amount of food. However, the more variety you control, the more effective they will be, you will gain a percentage-based global bonus of food production.
Similarly, Material Resources (Old Growth Woods, Quarries, Clay Pits, and... let's say... Timber Lakes) work similar.
Economic resources is where you should go really nuts. Having gold mines everywhere is a bit simplistic and reminds me of Warcraft II. Instead, Economic resources provide Trade Goods, which generates commerce and makes gold. If you wanted to be really awesome, the resource's value can fluctuate depending on it's availability, how much it is monopolized, etc.
Some sample economic resources: Wool, Silk, Cotton, Fur, Silver, Copper, Gold, Spices, Artifacts, Dye, Gems, Ivory, Sugar.
I still think, by the way, it should be a little more challenging to "balance the budget" than it is right now.
Idea #2: "Flavored" Merchants and Industries
Merchants should not be generic. They should actually be visually distinctive, depending on the surrounding resources. A town with a nearby silkworm farm (?) should be a tailor.
In addition, industries can be built over certain resources to make it into an economic resource. So Orchard can either be Food resource, or you can build a Wine Industry over it to make it an Economic Resource. Now, you don't get food from it, and if you suddenly need food you shouldn't just be able to pull it down and start making food again... you essentially have to wait for orchard to grow back, which can be a long time.
More ideas: Clay pits ==> Potteries. Quarries ==> Statue Maker.
Idea #3: Additional Magic Resources
Sulphur and Mercury can both make interesting magical resources in addition to crystals.
Idea #4: Special Items & Improvements for certain resources
Some resources unlock special items or building improvement. For example, Silk could unlock the Great Standard, a standard made of silk that inspires soldiers around it, or allow a player to build a Great Tailor who... does stuff... Or a Statue Maker could make a special kind of golem.