I'm having a wonderful time with my friends. (time - countable and uncountable. Countable here: occassion)

I really enjoy listening to music of all sorts on my iPod. (Music - talking in general)

We can provide accommodation for you in a comfortable hotel. (accommodation - uncountable (UK) speaking in general)

When I visit foreign cities, I really like shopping for clothes. (cities - plural: no article; I like/dislike + -ing)

Money can cause a lot of problems. (Money - talking in general)

I've got plenty of spare time at the moment, so we can have dinner together if you like. ("plenty of", "at the moment", meal in general - no article)

are the most effective means of transport. ("the" with superlatives)

... at the age of 16. (common expression: "at the age of ...")

on the Internet. (use "the" with things that are unique)

in the city centre (clear what we are referring to by the context)

Have you heard the latest news about ...? ("the" with superlatives)

I'm hoping to visit your town next year. (common expression "next year")