(Mexico at least)
Sometimes this is used in conjunction with "gracias," but it can stand on its own if you have to or want to be especially succinct. For example, I was a bit disoriented when driving in a strange city recently, pulled over to ask a woman who was standing on the corner chatting on the phone, noticed she was speaking in Spanish on the phone, and asked her in Spanish if I should turn at that corner to get to the bus station. It was possible I might find that I was blocking traffic, so I only said, "Muy amable." Where the full version is "Gracias, muy amable," or "Gracias, señora, muy amable." (Roughly equivalent to "Thank you, you're an angel.") This is not slang, it's gracious speech that anyone can use comfortably. (Not that I have anything against slang, but you need to know what is and what isn't slang.)
Note: I forgot to include a literal translation of "muy amable": [That is] very kind [of you].
(Esto / Ud.) me ayudó mucho
This would work in any language. If you want to show your appreciation for something someone did, or information provided, and you don't want to repeat "thank you" for the umpteenth time, you could say (This / You) was very helpful [for me].