See my avatar for another example. You'll notice that all these $8 chips are in some way related to lunar (or Chinese) new year. That's because 8 is a very lucky number in East Asian cultures. I don't think any $8 chips are used in circulation; they're intended as commemorative collectibles.
The Nexgen "lucky bee" mold is the way it is because, (1) bees represent skillfulness ("skillful as a bee" - basically, skillful is to bee as sly is to fox), and (2) there are 8 bees on the mold. The idea is, to win at poker, you need some combination of skillfulness and luck!
I don't think any $8 chips are used in circulation; they're intended as commemorative collectibles.
In Nevada, they are legal instruments of play and are accepted for all bets. Now the Pit may not like them (the chip trays usually have not slot for them)and players may not like them (in baccarat an $8 win will create the same commission as a $10 win, as they will not round-down to a $5 win!).