Whereas the demographics of an online giver are very attractive; upscale, well educated etc. they rarely give an additional gift.

Why? Is it because they were swayed by media outlets to give to a natural disaster (IE Katrina or the Asian Tsunami) and are not really involved with the nonprofit's cause? Another possibility is that donors who give online are often dumped into that charities DM file and are solicited by there standard DM methods. Maybe they should be segregated into online and offline and solicited separately. (If you're not already doing that).

This is the $64,000.00 question. How to break into this market in a meaningful way.