The two basic kinds of immortality available today may not satisfy those looking for the "after-life," but they are both very real and important, and there is a medical technology solution visible on the horizon that should satisfy many persons.
The first is the least satisfying - the partial immortality of your genes through your children. This is of no significance to the childless.
The second is the ancient notion of fame or kleos (κλέος) among the Greeks. When Homer sang of Achilles and Odysseus it was to give them undying fame, which they have today among many literate persons.
The third kind of immortality will result from a solution to the problem of aging, almost certainly from stem cell research, which should allow vital organ replacement, and from a cure for runaway cancer cells, which are a devastating entropic force.
This third should satisfy even Woody Allen, who famously said,
I don't want to achieve immortality through my work.
I want to achieve it through not dying.
The second kind we call "information immortality." It is more realizable than ever with the development of world-wide literacy through print and now through the world-wide web, which makes the Information Philosopher available anywhere. In five years time, a majority of the world's population will be carrying a smart phone and thus able to read this work.
The great
Wikipedia will be capable of having something about everyone who has made a contribution to human knowledge.
If we don't remember the past, we don't deserve to be remembered by the future.