Oh my goodness, the options are just endless!!
If you're thinking about toys, there are a few I'd highly recommend!
Climbing Frame for Hamsters from Natural Wood | Top deals on small pet accessories at zooplus
This one Bubblesky just LOVES. I have no idea why as it seems quite a boring thing to me but there we go! I pulled off the bells as I wasn't sure it they were hamster safe, and I also painted the top with plastikote to make it look like the stands were mushrooms! I hide treats at the top of it frequently and Bubblesky makes her way up very quickly now! At first she was a little unsure, however, now it must be her absolute favourite toy. You could even paint the tops like little round santas, or baubles? Go wild!
Tunnels & Dens: Sputnik Hanging Den | Small pet accessories at zooplus
Although I don't own this myself, I have heard only good things about it! Apparently most little furries just love it!
Birger Small Pet Playhouse: Free P&P on orders £29+ at zooplus!
No idea what this is like as I literally just found it but it looks like mega fun! You could paint it with plastikote to make it themed Christmassy or like a Santa's Cabin! And hide treats in different places to encourage hamsters to use the whole toy! Dunno whether it'd be big enough for Sweep but you could definitely give it a try.
Apart from toys there are loads of fantastic treats, wheels, dens, cages.... I mean, anything new is exciting right?? You don't have to spend loads of money, either, if you hunt around charity shops and bargain stores they often have things that a perfectly suited to hamsters. Wax melt holders are a great example - if you get them from somewhere like B + M they're cheap and safe.