Higher-resolution file here (.wmv file, 13.5MB).
To make this shape, I took forty-one circles of latitude on a sphere and replaced each one with a heart. The scale factors of the hearts are the same as the scale factors of the corresponding circles of latitude. In that sense, the shape is an example of a generalization of the sphere, in which a stack of similar circles is replaced by a stack of other similar shapes. (My wife and I were talking about this subject the other day.)
The parametric equation of a heart is from this page. Some other nice heart ideas are here.
(Don't worry, honey, I also bought you a non-mathematical present!)