I love castor oil. It is a humectant, so it is very moisturising when added to water. It also appears to thicken and strengthen hair.
These are the ways I use it:
1) Add to my homemade spritz (along with water, glycerine, etc)
2) Add it to my leave-in (It worked very well with Garnier Fructis Smooth and Shine / Repair and Shine)
3) Dip a Q-tip in it, and use it on my eye brows and eyelashes. (It definitely gave my eyebrows a thicker, more defined line - it's hard to tell with the lashes)
4) Add to mascara for lashes
5) Apply to scalp (maybe mixed with more spreadable oils or MegaTek Rebuilder, or whatever else you want)
6) Rub a bit on my face when I have a little breakout, or can feel one coming just beneath the skin (it really does help dry them up/ prevent them from surfacing - at least for me!)
I find that the clear pharmacy version works fine for me, although I get the dark version from Jamaica when I can.
SOmeone asked in an incredulous way about washing face with oils. You know it's funny, if you go on "mixing" sites like lotioncrafters and camdengrey, you'll discover that oils and fats form a large component of all soaps. It makes sense if you think about it - you need something to kind of lift and "slip" the dirt off, and that will float off when washed with water.