I sewed up some simple ribbon suspenders recently. You can find a tutorial for boys suspenders on the cotton and curls blog. She used elastic for the suspenders, but ours are just made out of ribbon.
I added a bit of contrast stitching on Miles'; I wish that I'd added it to Clark's as well.
I think that suspenders and bow ties are a fantastic pair. They help break up the torso, and add a bit of visual balance.
And with the lack of boys accessories out there, why not make some up. They are simple and quick to make, and are really fun for photo shoots in the back yard.
Thanks for reading, happy sewing, and a happy Memorial Day also!