I discovered Allium 'summer beauty' a few years ago and fell in love. Strangely, it was the foliage that first struck me...long, narrow slightly twisted leaves (similar to daffodil foliage) compact and beautiful spring through fall. The very light pink, almost white round flower clusters pop up in late July/early August.
It's not only beautiful but also drought tolerant (one of the few plants in my garden this year that still looks amazing...it's been hot and dry in Iowa), plus can be divided. These were pretty rare a few years ago, so I had to buy one at an auction. Every couple of years I gently divide it in hopes of having more beauty all summer.
Oh, and to top it off, I just found out that Midwest Groundcovers now has a smaller cultivar available called Allium summer peek-a-boo™. It only get's better!