The skin on the tip of my big toe is darkening, i've had an ingrown toe nail but that was about 1-2 years ago and healed since then, or so i thought.

Needs care: its very hard to determine what's going on from the information you have given. I'd recommend you have it checked out

Ingrown nail: This sounds indeed like your nail may me in grown again. See your doctor to talk about permanently removing all or a portion of the nail if this is reoccurring problem. Also, make sure your shoes are the correct width, too narrow shoes are a common cause of ingrown nails.

It depends on the ca: I depends on how dark it is. if it is dark brown or black let us know the size...is it a well defined patch??? It may need a biopsy if it looks like a mole. If it is changing in size or color over the next 3-6 months, you should seek medical examination, preferably by a dermatologist who has to decide if to do a biopsy.