Things you cannot do with one hand:
1) put on rubber gloves
2) remove rubber gloves
3) use a pepper grinder (for grinding pepper... you probably could use it for other things)**
4) do up tricky buttons. Normal buttons ok.
Things that you surprisingly can do with one hand:
1) drive a car. No one told me not to.
2) remove a contraceptive implant
3) i'm pretty sure I could remove a skin cancer too but they wouldn't let me try
4) cut the fingernails of a squirming one year old (with judicious use of both feet and superior body weight)
5) move furniture
6) tie up hair with a hair tie. Not perfectly, but neater than John using both hands.
Things you can't do, unrelated to number of hands:
1) fix a tent pole, first try, without swearing. Stupid elasticated elastic.
**actually you can use a pepper grinder, but only if you put it between your knees and put the saucepan on the floor and it's not worth that.