Frank:
It is my understanding that natural selection requires a benefit to go along with a change to the species or else the change does not grow in the host population. So calling sickle cell an example of natural selection is by inference calling it a benefit. A defect is suppose to decrease in the host populations where a benefit grows in the population. If I am wrong in my interpretation of theory then let me know.
Well, zoegirl said it better than I could. But let me try to clarify things a little further. Sickle cell - the disease - is not a beneficial condition. As you point out, there are complications that typically lead to an early death in someone carrying 2 copies of the mutant allele. However, because it is codominant (as opposed to total dominance and recessiveness) things are different in the carrier. They have virtually no ill effects associated with the disease. But they produce 50% mutant proteins, and this is enough to be beneficial when faced with infection from the
Plasmodium parasite. Without the selective agent, carriers have no advantage over people with 2 copies of the normal gene - but in areas where malaria is endemic, they have a selective advantage. And both are better than having sickle cell disease, whatever the conditions are that exist. So - disease = bad, normal = good, carrier = no benefit to beneficial depending on the conditions. Does this make sense? It is for this reason that the allele frequencies are so high in areas where malaria exists - the carriers are surviving better than they would in populations where they had no selective advantage.
So you have no problem with man's interference with the natural order. Then we can make drugs and try and prolong life even though it may affect the gene pool in unnatural ways. So we should prevent suffering where we can.
Well, in a simple and limited sense, yes.
How about genetic engineered foods, should we continue to make changes to our foods to make some plants more resistant to pest and desease. Should we try and increase the vitamin content of our produce?
Well, I have mixed views on this. In one sense, it is the next logical manifestation of agricultural processes we have been practicing for millenia. On the other hand, I am personally not convinced that we have thought through the ethical implications, and we have not adequately tested the health risks and benefits, nor do we fully understand the consequences of releasing these organisms into the wild. So I think the idea of GM foods is intriguing, but I am not of the opinion that I want one in my backyard just yet. But then again, my opinion is inconsequential; 75% of processed food products on the market today contain some amount of
GM food in them. Can you say Pandora's box?
If man made a nanobot that destroyed all malaria parasites would you oppose the release of this device because it would make a natural organism extinct?
No. I'm fine with this. It'll never happen, but it would be nice for humanity if it did.
Should Congress step in because the release of the nanobot would cause a lifeform to go extinct, could the endangered species act be used to save the malaria parasite?
Well, as far as I know, the ESA only applies to critters existing in the US. So I think Congress would be overstepping their authority if they did this. But if your question applies to pest species X that does exist in the US, I'd say (a) they'll never drive a bacterial, insect or protistan pest species to extinction so why worry and (b) isn't this what pest control specialists try to do now with roaches, ants and termites?
I think of nature as made for man and we can do what we want so it benefits us.
Well, I know biblical scripture makes this proclamation. But I think things are a little more complicated than this. It might have been easier in the Garden of Eden when only 2 people lived on earth - but how do we decide what is appropriate and inappropriate use of god's creation? Surely my singular views may differ than those of a Chinese peasant farmer, a CEO of a mining company and a zoologist.
Frank, we are quickly wandering into areas well outside my area of expertise - and I meant no offense in what I wrote. So I am sorry if I upset you. I can explain the biology and I am happy do a little metaphysical navel gazing with you, but I think I am well outside my comfort level when it comes to your religious beliefs. So just let me know when I've written something that offends you and I'll try and sort it out. But I am pretty sure I can't answer questions like "if humans are still evolving, does this mean they are no longer in god's image". There are likely lots of folks here with far more training in theological and scriptural issues who can answer them far more eloquently than I. Does this help?
). But I am not shocked by these findings nor should we be, I think. Even in the strictest creation models, why in the world would God have created species that couldn't withstand natural fluctuations in weather and geography? Would He not have created them with the genetic flexibility in their populations to withstand these changes? Wouldn't the absence of such flexibility be a poor design with respect to ecology and populations? 
BUt I won't quibble with semantics,
) I am still a skeptic with regards to that leap from observable tests of mutations to "over time". Speciation is great, but does it account for the events in the past. I think this phrase "over time" tends to be easily used and, with regards to much of *historical* evolution, still in the realm of speculation. But I do not dismiss them because of any theological or philosophical application. But, we have covered my views 
already.