, which is a bit like VoiceThread. You can embed the code of the online presentation into Moodle like you can with Youtube videos etc. Also, if you want to do it yourself and turn Powerpoint slides into video, there's Camtasia (mentioned above) and Adobe Captivate (both expensive!), but there's a few free screen recording tools around, eg TipCam from Utipu
Also, I've used the freebies from Microsoft....
Photostory (export your PPT slides as image files; import into Photostory, add narration over each slide, transitions, output as WMV)
Movie Maker (as above, but more complex)
for Powerpoint, but use pre-recorded audio, outputs as WMV).
Hope that helps!