Talking about good ideas

With friends, at work and in many other situations we ask for ideas and respond to them. Here are some useful ways of saying you like someone's idea.

That's a great idea.
That's an idea.
Good idea!
What a great idea!
I think that's a fantastic idea.
I like that idea.
I like the idea of that.
That's not a bad idea.
You know what? That's a good idea.
Cool!

Explanations

• 1 and 2 are very common expressions. 2 has stress on THAT'S, and 1 can have double stress on THAT'S and GREAT.
• 3 Shows more enthusiasm, which is why it is a short expression. You can also say "Great"/"Fantastic"/"Wonderful idea" etc.
• The structure in 4 is very useful: What a/an/- + adjective + noun: "What a nice person"/"what a terrible mistake"/"What great shoes!"
• Adding 'I think' in 5 shows your personal appreciation, and we often stress 'I' to emphasize this.
• 6 and 7 are similar, but we stress LIKE in 6, and normally IDEA in 7.
• 8 is a variant of 6. We often use a negative structure (not + negative adjective: it's not uncommon, it's not impossible, it's not unlikely) for a positive effect for emphasis.
• 9 uses a rhetorical question: "You know what (I think)?" This is also a strong way of giving your opinion of something.
• 10 This is a common informal way of saying you like an idea or suggestion.