in RL people have a certain 6th sense when it comes to things that they know really well...
if a Miner walks by a pile of earth, he can tell if that kind of soil is rich or not in gold/silver/iron...
a worrior can \"sense\" danger by being close to other warriors/monsters...
a fisherman can tell if he is going to catcth fish by looking at the river...
that is experience...and i have a thought of how it could be achieved in PS.
auras...i know...it seems like crap

but, if you have a lot of mining skill, you should be able to better see if that soil is of any good to be mined (mining skill also increases your ability to mine, of course), for that i suggest for example a yellow (or any other colour) aura on \"good\" soil. This aura would be undistinguishable if you were a lvl 2 or 3 miner, but you would be able to notice it if you were a lvl 15-20... (at 1000 you would be blind from the glow

)
worriors could have a sense that showed danger, like spiderman\'s spidersign (or something) a red aura in from the location of the danger...
other kind of skills could have another kind of \"aura\"
i think it would be a kind of reward for you investing in a skill.... :]