Touch sensitive LED screen, leather, mahogany, anodised magic.
The Genus Type R is very nice if you can find one. Going for a very reasonable £50 on fleabay. (I paid nearly triple that last year)
Not really a 'favourite', but an interesting example that transcends languages across the globe and is such a good logo they keep it despite it being a byword for US imperialism and crap burgers.
Again, not a 'favourite', but a good example of a symbol that has been used for as long as humans have existed. Cave paintings, tribal art, etc. It's a protector, agressor, sign of power.