It is easy do color correction/grading (Add -> Effect Strip -> Adjustment Layer, then Modifiers -> Add Strip Modifier -> Curves). This can be used for instance to give a "sunset look" to an amateur video that had a blueish look.
Once I have created some color curves, how can I export them so that they can be imported and re-used in different projects?
I would encourage you to start with the CDL node, as it is easy to replicate and generate looks that can be loaded with OpenColorIO.
If you are using a complex node chain to modify an image, you can reuse your crafted looks. It will require a bit of learning and patience. If you wish to dive into this subject, feel free to wade through this longwinded post written by an idiot. Also note, Blender's curves (and the entire UI) isn't colour managed by and as a result it is not likely responding the way that one might believe it is.
Any node or node set can be saved as its own reusable entity. Just select the curve node and hit ctrl-G and you can name and reuse the node group in any other material using shift-A / Search or Groups.
Something very much like this: Grab shader color to mix in another shader?
In addition, you can gather those node groups in a blend file and link them from other blend file. Basically creating your own library: How to import Downloaded Materials/Files?
