Blogger Brian Blum is touting a new web-based genealogy app: Geni:
Every time you add a name, you can include an email address. Geni then sends a message inviting that person to join your tree and start entering data of his or her own. In that way, your family tree grows as other people do the heavy lifting. Geni sends out an email summary of every week of who's joined and allows you to enter missing addresses directly into the email.Worth a visit and sign-up, I'd say.
To give you an example, I started by entering 21 names into Geni. I knew the email addresses of 15 of those people and they were automatically invited, a number of whom immediately began filling in their part of the tree. After about 3 weeks of using Geni, there are now 472 people in my tree dating as far back as the 1850s – to my great-great grandfather who lived in Berlad Romania – and as far a field as my aunt's ex-husband's sister's family. That comes out to 115 blood relatives and 356 in-laws.
More Jewish genealogy resources are here.