One way to share what data you have and note what data you need is to post your genealogy on the web. Before you do that, however, please read the Guidelines For Publishing Web Pages On The Internet. This document sets out the best ways to make your page findable and useable by other genealogists.
How do you publish? Almost every genealogy database program has an HTML option for printing reports. However, you can simply print the text of an Ahnentafel to a file and paste it into an HTML page, as I’ve done here. Note that though I did mention two living people, the essential data is excluded, to help prevent identity theft. Most genealogy programs allow you to simply exclude any living person from any report.
That brings up another point, that is very, very important. Some folks are afraid that their data might be “stolen” from the Internet, so they delibrately insert factual errors on their web pages.
Dont. Do. That.
If you have data you want to keep in reserve for future information swaps, simply omit it. If you have data you want to keep private until you publish your hardbound, limited edition genealogy, that’s fine. But do not ever publish anything, in print or online, that you know to be false. It’s extremely difficult to remove all traces of anything on the Web, and that incorrect information may linger longer than you do!