Just wanted to add a few things, firstly that women can actually donate eggs. It's not often done however, as it's a fairly invasive procedure compared to sperm donation (which should really go without saying). With that in mind I'd probably only be willing to donate eggs if I either met the people whom I was giving the donation to, or if I already know them (for example if a gay couple I was friends with asked for my eggs). Even so, I'd have to really think about it, and whether I wanted any input into the child's life or not. I'd also refuse to actually carry the child, they can have my eggs, but I'm not getting fat and going through the rigors of childbirth only to produce someone else's kid.
Also, I looked at sperm donation in one of my classes a few years ago, and one thing that our readings pointed out was that even if any offspring did not want to find their biological fathers for emotional reasons, many still wanted to for practical ones. Specifically, it's impossible for someone to have a complete medical history, when they know nothing about the person who provided half their DNA. They may have come to terms with the fact that the people who raised them are not their biological parents, but they might still need to know whether they're at risk for certain types of cancer or inheritable diseases. I guess it depends on the screening process at the clinic and the country's laws, whether this is an issue or not.