Well I've tried all that has been mentioned, here's what i've discovered:
1) Viagra - was given from a friend who had it prescribed to him (about $15/pill). Like Jacques says, you gotta have it on an empty stomach otherwise you're wasting your money. Made me feel like I was a teenager again, getting hard at just the thought of fooling around. I didn't maintain an erection all day but was able to get it up whenever I wanted for that day.
2) Cialis - a friend brought it from Mexico (converted to CDN $, was about the same as viagra). It's called 'the weekender' and for me, I didn't feel it take effect as fast as viagra but it definitely lasted a day longer than viagra.
Both medications gave me fuller, stiffer erections.
3) Ginseng - you have to take it on a regular basis (daily) and truly, I felt no different sexually. But I did have more energy from day to day.
4) Yohimbe - I would suggest reading
http://www.yohimbe.org/ I bought the cheap (actually not that cheap) stuff from GNC (in the US.. it's not sold in Canada) and it had the same effect as ginseng for me... in fact it upset my stomach. If someone could direct us to the true herb supplement with full potency than what has been watered down for the commercial market, it would be appreciated. Again, you have to take it on a regular basis to feel any difference.
The greatest thing I've found for myself was quitting smoking, regular exercise, a balanced diet and lots of rest can help a lot more than spending the hundreds that i have on supplements. But if I had to spend my money, I would go with Cialis for the long lasting effect.
That's my 2 cents.