Stamina
Speedo - you have rec'd some great suggestions here and I would like to add a few more.
Diet: (such a foul word) - but in all truth if you are asking your body for a rock hard, long lasting erection and at the same time it is trying to process a double quarter pounder with cheese, large fries and coke, you are probably not going to get the performance you want. Garbage in - Garbage out, type thing.
PC Excercise: These will increase your "staying power" and add pleasure to your finely tuned, well controlled climax.
You can do this by stopping your flow of urine, hold for 2 seconds, 5 seconds and so forth.
While sitting or standing, get yourself hard, drape a wash cloth over your erect penis and do "lifts". Once you master some smaller reps, increase the weight, you can use larger towels or wet smaller ones.
Um, if you can flip a wet beach towel over your shoulder, you've probably gone too far!
Remember, while toning muscles you can get sore, so be careful.
Last thing, I am not an herbalist or doctor, but I have researched my own sexuality for a very long time, and read many recommendations about adding a few items to your daily diet.
Fish Oil: RDA is 1600 mg - I use OmegaRx by Zone Labs (4 capsules) some people increase this as per your body weight.
A good mulit vitamin - like Centrum - as directed
ZMA (a magnesium/zinc) product (for men).
For woman - add
Calcium-1000mg/Magnesium-400mg/Zinc-15mg
For women who menstrate (have a period) add iron, about 10-15mg a day. ( I use Slow FE)
This things combined - assist blood flow, cardiovascular and brain function and helps your body process proteins for good use.
Also, it is wise to seek a doctors approval before using any meds or vitamins.
Also, soy proteins are bad for your libido and alter hormone levels - you may want to shy away from too much soy usage.
My cost is about $65.00 a month for this regimant.
It won't work for everyone, I am sure, but for me and a few men that have tried - it has really added pleasure before, during and after great sex!
Enjoy!