Whenever I go into my local Poundland I always look at their nail or makeup collection. Although I wouldn't buy the foundation or mascara, their liquid eyeliner is pretty decent for a quid and they have a nice selection of nail polishes.
As it's summer (I think), I opted for pastel shades 'Mint Milkshake' and 'Bambino Blue' (I know they look virtually the same in this pic, but I assure you they're not). You can view their full collection here. (I can definitely see the glittery ones getting me through the dull winter months).
I wouldn't say they're the most long-lasting (what do you expect for a pound?), but if you're like me and only paint your toenails - or your fingernails for special occasions - then these are definitely a bargain! They're just as good, if not better, than your standard high-street brand.