My 4 year old loves to play babies and all she wanted to do for her birthday was have a baby party. We sent invitation saying "Little Mommys: Bring Your Own Baby, childcare provided" with the date, time and location.  We prepared our den with all of our daughters baby doll furniture such as a cradle, rocking chair, strollers, infant carriers, clothes, bottles, "play" soaps, lotions, high chair, just whatever she already had. And sitting around we had baby bottles (which I purchased at Walmart for $.96 each) filled with candy tied to helium balloons. The adjoining room was decorated for a tea party and the other adjioning room, our playroom was set aside for our 7 year old son and male cousins. As the guests arrived with with babies and strollers in tow, they were brought to the "nursery" to play. After all guests arrived and had a few minutes to play they were asked to put their babies in childcare; each little mommy took her baby to our play room door where our son put a sticker on the baby's back with a number and gave each mommy a candy pager in case he had an emergency and needed to reach them. The girls were then taken to the tea party room where they were served chips, drinks and cupcakes on pastel plates in pink, blue and yellow.  Each cupcake had an icing bootie on it. After they were all finished eating and all presents were opened they went back to pick up their babies.  Where our son and a friends teenage daughter swaddled each baby in a new blanket and had given each baby a bracelet (which can be found in any party store as a cake decoration or gift tie 6 for $.99).  Then each mommy was photographed with her baby both draped in white (like the madonna pictures you have with your newborn).  This all took about 1 and 1/2 hours and the kids had a blast. Each child went home with a new baby blanket, a baby bottle full of candy, a balloon, and a little bracelet for their baby. In each thank you card I sent the madonna photo and a photo of all the girls with their babies together. We had a great time and my 4 year old got the party she wanted.  This was very simple, and in expensive and it gave our son and and my nephews something to do during this "girl" party. Some other ideas we thought of but decided did not work for us were: if your daughter is just getting into babydolls to use baby shower invitations stating that your daughter has her first babydoll then the guests will be likely to bring "baby stuff" as gifts. You can also have your guests make some kind of inexpensive frame as a craft and then when you print the pictures they can put it in the frame as a memory of the party, this was my intention but with 15 4-5 year olds you do not accomplish much in 90 minutes so I sent them home with the foam craft kit (OrientalTrading.com).  If you have time you might also try to "pamper" the little mommies by painting their fingernails and putting lip gloss on them, even playing dress up, little girls like to mimic mommy.  I believethis will always be a special memory for all of us and the girls who attended.