BATCH IMPORT images into PowerPoint
How can I batch import lots of pictures into PowerPoint?
If you have PowerPoint XP (2002) or higher you can choose Insert, Picture, From File and select multiple picture files. When you click OK, they'll all be inserted at one time onto the current slide.
But more likely you want one picture per slide. And it'd be nice if PowerPoint would insert new slides, one per image, right? Right. So read on ...
Free PowerPoint PhotoAlbums
If you have PowerPoint 2002 or 2003, you can choose Insert, Picture, New Photo Album. In PowerPoint 2007, choose Photo Album on the Insert tab. If you have PowerPoint 2000, use the free Microsoft Photo Album add-in for PowerPoint 2000. But before using Photo Albums, read this.
Other options
MVP Shyam Pillai has written an incredibly useful, full-featured Image Importer Wizard that lets you do virtually any sort of batch image import you might want. And if it doesn't, he's probably added the feature since I wrote this, so now it does.
Pixerter is a relative newcomer with some interesting features.
Mac users!
Macintosh Office MVP Jim Gordon has excellent batch picture importers:
Roll your own
If you're of the tinkering persuasion, you can build your own importer. This will get you started:
Batch Insert a folder full of pictures, one per slide
What's wrong with PhotoAlbum?
The PhotoAlbum feature in PowerPoint 2002/2003 (and the PhotoAlbum add-in for PowerPoint 2000) are free and offer a few features that the other suggestions above don't. But they also have a few drawbacks you should be aware of:
They don't import pictures. Instead, they create rectangles or other shapes, then fill them with pictures. This can cause other problems later (picture links break, you can't crop the pictures and PowerPoint can't compress the pictures the way it can with pictures inserted from file.).
If you use PhotoAlbum, at the very least, be sure to insert the images rather than linking to them. The links it creates will almost surely break if you move the presentation, and they're not repairable the way regular links to inserted picture files are.
On the bright side, if you apply animation effects to the inserted pictures then decide to use a different picture, you only have to right-click, choose Format, and choose another picture for the picture fill. The animations won't be lost.
The Photo Album feature in PowerPoint 2007 inserts pictures rather than picture-filled shapes, and even if you choose the Link option when inserting the pictures, it ignores you and embeds them (!) so none of the warnings above apply.
So if you use PPT 2007, you're good to go. And in earlier versions, as long as you don't link the photos and don't need to crop or compress them, you're also good to go.
If you later need to compress images inserted this way, there's a macro here that'll help: