Cultural Themes

An educational and fun theme that's also kid-friendly is designating a cultural theme in a specific room or wall. When my friend bought a three-bedroom house, he selected an African, Hispanic, and Asian theme for every room. You can even create a menu based on a cultural theme. Maybe invite friends over once a month, and everyone brings a dish from the selected region. You can do this once a month or once a week according to your preference.

Book Swaps

If you have too many books you're no longer interested in, you can throw a book swap among your friends. You can offer a finger food menu or ask everyone to bring a dish and any books they're willing to swap. There are also book swaps available in many cities, as well. Check with your city or local library.

Movie Lovers

For movie lovers, consider creating a gift basket centered around that theme for birthday or Christmas presents.

Two or three favorite movies and I like adding a wild card (a movie you think s/he might like)
Gourmet Popcorn
A selection of concession stand candy (I recommend a combination of chewy, chocolately, sweet, and sour combination)
Soda
Maybe even something salty and crunchy like chips

Pick a Birthday Theme

Pick a theme. It creates a focal point. The menu, card invitations, and decorations can be centered and organized around it. Here are some ideas:

Baker (Cookie Theme)
Beauty Party
Bookworm
Food Lover (Pasta, Sushi, Hors 'd Ouevres, Lemons, Apples, Cheese, or Chocolate Theme)
Knitting
Jewelry Making
Movie Marathon
Scrapbooking

Gift Baskets: For Food Lovers

For a simple and affordable gift for food lovers, create a gift basket that contains homemade jam, bread, vinegar, marinated olives, beef jerky, etc. You can even narrow it down to a specific ingredient such as raspberries (raspberry jam, raspberry jellies, raspberry vinegar, dried raspberries, etc.)