Windows 7
As most of my family is still using Windows, despite my best efforts to swing them over to Linux, I think they should understand why I want a copy of the Windows 7 upgrade -- especially while it's $50.00.
iLife 09
This one would be a harder sell, but I think the promise of family-friendly DVDs of family events should be enough, and it doesn't hurt that none of them would know that I already have all of the software, just in an older version.
iWork 09
Now, I don't know if I actually want a copy of iWork, because I use OpenOffice.org, Textmate, and WriteRoom for just about everything. My only regret is that I do not have good -- and pretty -- presentation software.
Mobile Me
This is the most sketchy one... I don't eve know why I want it... I think it's mostly because of the Reality Distortion Field, and the fact that I had a subscription that has now lapsed, and I really want my Mac to stop nagging me about it. However, if I do ever break down, switch to AT&T, and get an iPhone, I'll actually have a use for MobileMe beyond Yet Another Backup. (I'm already using MOZY, DropBox, Live Mesh Beta, and network-attached storage.)