Play with it a bit...you may find you like the effect it gives.
Lay it over a picture/photo, journaling, use it as a frame. Or layer it under the photo but over something you want to use that is distracting the layout or card.
Journalize on velum, I print it with my printer or you can stamp on it.
Use it as a background over very busy paper to tone it down. The pattern will show through but not be overwhelming. I don't cover the whole page - sometimes 1/2 page or leave 2" border of busy-ness all around.
I use to use vellum a lot and for all the reasons mentioned, journaling, printing pictures on it, toning down backgrounds. I still use it occasionally like this layout where I wanted something that felt light and subtle. Just Dance By Sewflake
I don't use vellum too often but when I do it's usually as background. I like printing photos on it. For this WWII reenactment page I printed a photo I took of a background scene and then layered it on top of a camouflage printed paper. It gave a nice transparent affect.
For this one I took a stock photo of my new mixer and printed it out on vellum to use as a focal background for my page. I like that translucency that you get with printed vellum. Instead of making it look like a printed photo, it looks more like background paper.
And for this one I used a printed vellum sheet from a paper pad as a background of clouds.
I use vellum just like any other paper now....diecut frames, tags, titles...use as a layer under photos...make flowers, pinwheels, other embellishments....
You can print your journaling or your photo onto the vellum as others have suggested....
You can also print patterns onto the vellum with your printer and then diecut or you can stamp or heat emboss onto the vellum....
Try running the vellum through your embossing folders for a really cool look!
You can make a little pocket to stick a tag with journaling or you can make one of the 'confetti pockets' that are popular right now!