There are a whole host of foams, creams, and jellies which are laced with spermicide to be used as contraception. They come with a plastic applicator, and should be applied deep inside the vagina, just outside the entrance to the cervix, for maximum protection. You can also use the jellies as extra lubrication during anal sex. Use the creams and jellies with male or female condoms, and with the diaphragm and cervical cap. Creams, jellies, and foam are quick and easy, and relatively inexpensive.
Many people feel itching or burning sensations with certain brands of cream, foam, or jelly.
Make sure you test a given brand before smearing it all over your tender areas, or you may find yourself springing unceremoniously from the bed, howling and dashing for the bathroom. Second, these products tend to have an unpleasant taste, so you may want to apply them after oral sex. Spermicides break the mucus down instead of working with it to block and kill the sperm. I find these products somewhat distracting during sex, unless I make them part of the sex play. You may want to do the same.