Julienne applications

I don't know if I'd consider the cut I use for stir fries to be a jullienne, as I tend to make 'em a little larger, as I like a little bite left in my vegetables. (I consider julienne to be at most 1/10 of an inch / 2.5mm across ... I cut my carrots for stir fries at maybe 5mm across)

I tend to julienne when adding vegetables to cole slaw-like salads (or even apples and other firm-fleshed fruits).

If you like really crispy fried potatoes, you can julienne the potato before frying to make 'matchstick potatoes'.

Many professional chefs will have a mandoline, and so if they're preparing large amounts of something, they'll use that, rather than a knife. (and you can get longer strips that way ... the full way down a large zucchini or long cucumber, which would be difficult with even a long knife).

Julienne is also just a step before finely diced items, so technically, I'll pass through that phase when cutting up carrots for mirepoix.

... all that being said -- you're probably most likely to encounter the term when dealing with fancier french cooking or "gourmet" type recipes where you're trying to impress a dinner party. "Home" cookbooks are less likely to get into complicated knife tasks.

I find the julienne cuts work best in stir fries eaten with noodles as all the elements are long and thin and this seems to make them mix better.

but this might just be my imagination wanting it to be better...

I like to use a small amount of julienne-cut raw zucchini in my zucchini soup. Of course it's part decoration, but it definitely adds something to the mouth feel as well.