I discovered this interesting website in my flickr travels - it will make collages out of any photos you want in seconds. It does the usual rectangle or square shape, but then you can have some fun and make up your own shapes as well. In honour of the impending V-day celebrations, I went with LOVE and a heart. Gagging is allowed.
You can see their web address on the images (that's too bad... I guess you have to buy the full version to have that removed) but you can get your own here.