Perceptive forum discussions on Penetration:

Do any women cum from anal stimulation alone?
If so does it normally take longer or shorter than vaginal penetration. Is it a different type of orgasm?

Too flimsy?
To anyone who has used a harness and dildo for vaginal penetration, have you ever felt that maybe the dildo was too flimsy? I came across this issue.

Large or medium pure plug? Is double penetration possible with either?
I've been on the fence between Njoy's large pure plug and their medium pure plug for months now. I've got plenty of anal experience, so I'm sure I...

How often do you orgasm...
...from only penetration?

Is it 'normal' to not be able to orgasm unless it's through clitoral stimulation?

Good sex positions for squirting and g-spot stimulation
I'm able to make my girlfriend squirt quite easily with my fingers, but I can't make her squirt with standard penetration, nor can I make her orgasm..

There are lots of double penetration toys here.