4 Year Old Birthday Girl

books are always a hit for my 4 year old. Color wonders or some other creative/crafty item that gets used up. That way it is a gift but not one that they have to wonder in 2 months what to do with.
My nieces and nephews (1,3,5,7) I started giving $1 for every year old that they got to spend. their mom then to them to the dollar store. they had fun picking something out and it teaches a little of value of money and mom didn't feel bad throwing it when it broke.

Gift card to Toy R Us or Target, kids have a blast picking out something for themselves that they can pay for.

books or craft kits. my 4 year old and all of her friends love any kind of crafts.

I have an almost 4 year old, and while she'd LOVE to buy something with a gift card, I don't think she yet understands that "this was a birthday gift for you, they gave you a gift card". The connection isnt quite there yet...
Instead of going to toys r us or target where most of her gifts will be from, see if there's a "creative kidstuff" store in your area. They'll have the most unique & educational gifts for kids.
The other idea I can give you is to go to a book store (barnes & noble)? My aunt just brought a massive paper doll book for my daughter...and she's been playing with it every single day! I haven't seen paper dolls since I was a kid, but they've upgraded since then.

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Tickets/gift certificates for activities/plays....movies or theater, indoor play places, skating, bowling, zoo, aquarium, etc.

We also just had a party for our 4 yr old daughter and are the same as your friend, we would like to say no more toys, please! but we know that's rude, so if people asked us what she wanted or needed we said clothes or movies. We got tons of both and she loved it all. Also got some crafty type projects from Michael's or such. Also, we bought our daughter a subscription for a Highlights magazine that is age appropriate for her. No matter how big or small, she'll love it.

A fun box of places to go and things to do. I did this for my nephews once Christmas. $5 gc to Chuck e cheese, $5 gc for Barnes & Noble, $5 gc for the movies. $5 gc for the ice cream shop

How about hair accessories or a purse? My daughters love purses/bags etc to carry things around in. In craft stores you can find bags with markers so kids can decorate the outside of them. My daughters (3 & 6) love to paint. We buy sets of animals (usually 6 small figurines) in craft stores and they are pretty affordable. Board games like HiHo Cherry-O or Memory.

Zoobles
Strawberry Shortcake dolls / DVDs

My son also turned four this year. I gave a few of his friends (girls and boys) the game "Playful Patterns" for their birthdays and their moms all told me they love it. My son loves it too. It really is a great gift! You can get it here:

http://www.discoverytoyslink.com/karenchao