My most recent woodworking project was also the toughest one to assemble. This time around, I built a garden trellis to support the beans and peas my wife planted. Here's a picture (click for a view of the whole thing):
The legs and horizontal frames are all cut with compound miters at 7 degrees. This made assembly difficult, as there weren't any "flat" surfaces on which I could clamp things together. I purchased a cheap pneumatic nail gun which helped tremendously with this, but it was still a challenge. In the end, I think the final product looks pretty nice. Woodworking is a real fun hobby!