Shower Theme
This theme is not too original, but can still be fun. Ask your guests to dress in rainy weather gear. For example, yellow raincoat, gum boots, or rain hat. You could put the gifts in a large golf umbrella decorated with ribbons and bows.

Tea Party
This is the time to break out the china you haven't used in ages. Weather permitting, you could host the tea party shower outside. Arrange several small round tables in your backyard, cover with lace or floral table cloths, flowers and of course, tea cups and plates. A buffet filled with fruit, crackers/cheese, small sandwiches, croissants, salads, and tasty dessert squares will surely be devoured.

Teddy Bear Picnic
You can use the ideas from the tea party theme or actually use picnic decorations; checkered table cloth, balloons, summer plates/utensils. Place teddy bears on tables and around your yard or room.

Expectant Mothers
Just to make the mommy-to-be feel the same as others, you can ask your guests to fill their shirts with a pillow to give the impression they're pregnant. This could be fun if it's a couples shower and the men are willing to go along with the theme.

Diapers, Diapers, Diapers
Encourage guests to bring diapers for the expectant mother. This will set her on her way to having a great supply of diapers for the next few months. You could send out invitations reflecting the theme, as well as decorating your home with diapers. A fun idea is to fold your napkins like a diaper, keeping them together with a diaper pin.

Hollywood Star
Make the mother-to-be feel extra special by changing your living room into a movie set and your front path into a star walk. You could place stars on your sidewalk with the names of the guests and your living room could have movie posters or posters with the mother-to-be (if you have the extra pennies to spare), as well as a glitter ball and other items to glam up the room. Be creative with your food choices and have champagne and sparkling wine on hand to toast the occasion. Ask your guests to dress the part by coming in their fanciest closes or to dress as their favorite actress/actor.