Here is the traditional list of who pays for what in the wedding. Of course, today's couples can decide to personalize this list and let anyone pay for the portion they can or want to cover.

Bride

The Groom's wedding ring.
The Groom's wedding gift.
Gifts for the bridal attendants.
Personal stationery.
Medical examination and blood test for marriage license.
Accommodations for out-of-town attendants.

Groom

The Bride's engagement and wedding rings.
The Bride's wedding gift.
Gifts for the best man and ushers.
Groom's wedding attire.
Gifts for the groom's attendants.
Bride's bouquet and going away corsage.
Boutonnieres for attendants and fathers.
Corsages for the mothers, stepmothers, grandmothers, and other honored women
Medical examination and blood test for the marriage license.
Marriage license.
Clergymen's fee.
Honeymoon expenses.

Bride and Groom Jointly

Gifts of appreciation for parents or others who helped with the wedding.
Expenses of items desired which have exceeded original budget allocations.

Bride's Family

The Engagement party.
The wedding coordinator (if applicable)
Ceremony cost: location, music, rentals, and all related expenses.
Entire cost of reception: food, beverage, entertainment, rental items, decorations, wedding cake.
Bride's wedding attire and accessories.
A wedding gift for the bride and groom.
Wedding invitations, Save-the-Date cards, announcements and mailing costs.
Postgage for the invitations, announcements and other mailed items.
The Bridesmaids' bouquets.
The flower girl's bouquets.
Transportation for the wedding day.
Bridal brunch on the morning of the wedding.
Photography and Videography.
Personal wedding attire.
Floral decorations.
Favors
Special items such as unity candle, ring bearers pillow, toasting goblets, etc.
Taxes and tips
Travel and lodging for their guests (optional)

Groom's Family

Rehearsal expenses.
Rehearsal dinner party (including menu, drinks, invitations, decor, etc)
Personal wedding attire.
Travel and accommodations for groom's family.
Wedding gift for the bride and groom.
Special sentimental items: unity candle, toasting flutes, ring pillow
Any general expense they wish to contribute.
Taxes and Tips

Attendants

Wedding attire for themselves.
Fittings and alterations.
Wedding day salon trip for hair, nails, etc.
Any travel or lodging expenses.
Wedding gift for bride and groom.
Showers
Bachelor/Bachelorette parties.