Love love love stockings and I love love love a stocking thread! (long post alert! :D)
I'm a bit of a stocking fiend. My mum was excellent at making up stockings when I was small - I can still remember some of my little stocking presents, which were small and inexpensive but typically inventive or unusual - think wooden puzzles, mini musical instruments, a gyroscope, puppets, light up bouncy balls, small Body Shop fruit soaps to make the stocking smell lovely (to this day the smell of Christmas for me is a mixture of Body Shop strawberry and banana fruit soaps....) Or that 80s excitement, soap on a rope!
I start picking things up in the sales in January - before that even. I've bought a couple of things in recent weeks which are a bit too small/not age appropriate for DD now, but which she can have next year 
I aim to spend about £20-ish, and I always put in a satsuma, apple, choc coins, and at least one other eatable thing if not more, e.g. mini iced biscuits, choc reindeer, sugar mouse, Niederegger bauble (too expensive at full price but John Lewis often reduces them dramatically in the last few days just before Xmas as they have the year on). Also to go in each year is some bath stuff or bath toy, a small soft toy, a magazine or small book, and some kind of hair slides or bobbles.
My Dad always put nuts in our stockings too which we were all a bit confused by!
I then fill up the rest of the stocking with small wooden toys or puzzles, musical instruments and similar. I tend to go for just toys and novelties rather than anything practical - I put some bibs and socks in DD's first stocking when she was one, and her look of baby disdain was so comical! She is not a child who is backward about coming forward IYSWIM so I dread the reaction were she to find a toothbrush from Father Christmas (especially as brushing her teeth is currently her very least favourite activity....)
DD is three and so far for her stocking I have:
- a Miki mini soft toy penguin and mini book which I bought ages ago (like two years ago) - turns out M&S has bought the rights to the Miki illustrations for their Polar Bear and Penguin range this year, so I've also got her some mini iced biscuits and sweets from that range to match;
- colour changing bath ducks, Tiger (£3 I think?)
- fluffy socks, £2 in last year's Xmas sale in Baby Gap (hope they fit...)
- mini castanets, £2 in local toy shop closing down sale
- mini wooden kaleidoscope, local museum
- mini red wooden Carousel maraca, 30p in Tesco sale box!
- red hair slides and glitter hair ties, Tiger
- Lindt mini choc bear, 30p Sainsburys
- net of silver choc coins, 67p Sainburys
- wooden push-up toy, £2 Tiger
- finger puppets, £4 Ikea
- pack of Crayola crayons, £2
- snap card game, £1.50 ELC sale
- sachet of coloured fizzing bath crackles, £1 in the baby bath section in Boots
- I was also going to put in the free mini Christmas bunny toy I got last weekend in the JoJo store sale event goody bag.
Gosh I think I've overdone it a bit this year: I'm not sure if everything is going to fit in...! The magazine might have to go....last year it was an Abney and Teal one with a play phone and stickers and that was possibly the highlight of the stocking for DD though! (Thank goodness as DH and I both had noro on Christmas morning, bluerghh, so DD amused herself with Abney and Teal while DH and I took turns to dash to the bathroom....nice)
Kids' stockings are so nice to do; there is so much out there that is inexpensive but fun! Tiger is excellent for mini toys, also the John Lewis pocket money toys section for older kids. Museum shops or National Trust shops often have fab stocking tat (bug viewers, crystals, bouncy balls, solar butterflies for the garden, novelty pencils, Roman-style bracelets and so on). When I was an older teen I took to doing my younger siblings' stockings as well which was great fun.
If I have to do an adult stocking then I turn to books from the Book People (a short novel/collection of short stories, fun fact-y books like an almanac type thing), bath fizzers, bath bombs or mini hand creams, lipstick or balm, chocs, socks and nostalgic sweets, handkerchiefs for my dad, a wine bottle stopper, a Toblerone, sachets of garden flower or herb seeds. And a sugar mouse of course! :)