Inward, Christian Soldiers

Sex in Christ is a handy website devoted to Christian sex. It has tips on viagra, anal sex, threesomes, and oral sex, with relevant biblical quotations:

Jesus answered her, "If you knew the gift of God, and who it is that is saying to you, "Give me a drink,' you would have asked him, and he would have given you living water." 11 The woman said to him, "Sir, you have no bucket, and the well is deep. Where do you get that living water?...15 The woman said to him, "Sir, give me this water, so that I may never be thirsty or have to keep coming here to draw water." 16 Jesus said to her, "Go, call your husband, and come back." (John 4:10-16)

My favourite is this passage on 'Fisting and Gods will':

So far we have only discussed a husband fisting his wife, but some couples may wonder if it is appropriate for a wife to fist her husband if he enjoys anal stimulation. In most cases, a wife indulging her husband's desire to receive light anal play is not problematic in the context of a healthy sexual relationship. A wife may even anally penetrate her partner with a strap-on dildo if he enjoys this, and if their respective roles as husband and wife are secure outside of the bedroom.

However, because of the intense nature of the act of fisting and the degree of surrender and submission involved in being fisted, a couple should first look deeply into their own hearts and pray for guidance as to whether it is wise for the wife to fist the husband. They should undertake this only if their relationship is such that the husband can assume a submissive and passive role during a sexual act, while afterward still maintaining his role as the spiritual head of the household and leader in the marriage. Our article on Christian BDSM also addresses this issue.

So there you go.

(From a comment at Harry Hutton's site.)