P3DO is a viewer and manager for both 2D and 3D files and other types of file formats too.
Below is a list of all 40+ image and 38 3D file extensions viewed by P3DO. Icons beside each file format indicate what P3DO is able to do with each of them.

Image viewing     3D viewing     3D animation     3D Scene manager     View from ZIP/RAR     Writable

Image

.bmp .dib	Microsoft Windows Bitmap
.cel	Autodesk Cel
.crw	Digital Camera Raw format	icon
.cut	Dr. Halo
.dds	DirectDraw Surface
.dsi	Daz Studio Layered Image
.eps	Encapsulated PostScript
.gif	Compuserve Graphics Interchange
.ico	Microsoft Windows Icon
.icl	Icon Library File	icon
.icb	Truevision images
.jpg .jpeg	Joint Photographic Experts Group JFIF format
.jfif .jpe	JPEG JFIF Compliant
.pic	Autodesk Pic
.pcd	Kodak Photo-CD
.pcx .pcc	ZSoft Paintbrush
.png	Portable Network Graphic
.psd .pdd	Adobe Photoshop Bitmap
.pbm	Portable bitmap
.pgm	Portable Greymap
.ppm	Portable Pixelmap
.psp	Paint Shop Pro Image
.pxr	Pixar Image
.rgb .rgba	SGI true color
.rla	Wavefront RLA
.rpf	Rich Pixel Format
.rle	Microsoft Windows RLE bitmap
.rsr	Poser Rsr image
.scr	Word 5.x screen capture
.sgi	SGI Graphic
.tga	Truevision Targa
.tif .tiff	Tagged Interchange File Format
.tpl	Nintendo Texture Palette Library	(first texture)
.vda	Truevision images
.vst	Truevision images
.win	Truevision images
.wmf .emf	Microsoft Windows Metafile

3D Mesh

.cr2 .crz	Poser Figure
.hr2 .hrz	Poser Hair
.pp2 .ppz	Poser Prop
.pz3 .pzz	Poser Scene
.obj .obz	Wavefront Object
.duf	Daz Studio User file
.daz	Daz Studio Scene
.dzc	Daz Studio Content config	icon
.dzo	Daz Studio Object	icon
.dzm	Daz Studio Morphs	icon
.3dm .3dmf	3D Metafile	icon
.3ds	3D Studio Mesh	icon
.asc	3D Studio Ascii	icon
.prj	3D Studio Project file	icon
.max	3D Studio Max Scene	(Max shell dll)
.cob .coa	Caligari Truespace Object	icon
.dxf	Autocad Dxf	icon
.geo .obj	VideoScape (Mesh & Blender Obj)	icon
.iob	Imagine Object	icon
.iv	Open Inventor	icon
.lp	Lightscape Prep	icon
.lwo	LightWave Object	icon
.lxo	Luxology Modo	icon
.md2	Quake 2 model (1st frame)
.rbs	RealiMation RealiBase	icon
.rtg	Maya RTG	icon
.rwx	Active Worlds Renderware	icon
.sbp	ShopBot Part	icon
.scene	Sculpt3D Scene	icon
.stl	StereoLithography Interface Format	icon
.wrl	Virtual Reality Modeling Language	icon
.x	DirectX	icon
.x3d	Extensible 3D	icon
.xgl .zgl	OpenGL XGL/ZGL	icon
.qdm	Quidam Model
.xsi	Softimage|XSI	icon
.xyz	XYZ Format	icon
.veg	Vue d'Esprit Vegetation	(no update since Vue 6)
.vob	Vue d'Esprit Object
.vue	Vue d'Esprit Landscape
.car	Carrara Scene File
.rds	Ray Dream Studio	icon
.br4 to .br7	Bryce Scene	(with Bryce renders)
.br3	Bryce 3 Scene	icon
.brc	Bryce 2 Scene	icon
.obp	Bryce Object Library	icon
.cmx	The SIMs Description File	icon
.iff	The SIMs Object File
.skn	The SIMs Mesh File	icon

Texture / Material / Shader

.mt5 .mz5	Poser Material
.mc6 .mcz	Poser Material Collection
.bum	Poser Bump Map
.lt2 .ltz	Poser Light
.cm2 .cmz	Poser Camera
.mtl	Wavefront Object material	icon
.dzv	Daz Studio Value component	icon
.uvs	UVMapper Texture coordiantes	icon
.atm	Vue d'Esprit Atmosphere
.mat	Vue d'Esprit Material
.fnc	Vue d'Esprit Function File
.flt	Vue d'Esprit Filter	icon
.clr	Vue d'Esprit Color Map	icon
.cbr	Carrara Browser File
.brt	Bryce Texture Library	icon
.bsk	Bryce Sky/Fog Presets	icon
.mat	Bryce Material Library	icon
.shd	Bryce 2 Material Library	icon
.sky	Bryce 2 Sky/Fog Presets	icon
.flr	The SIMs Floor Texture
.lgt	The SIMs Light	icon

Motion

.pz2 .p2z	Poser Pose
.fc2 .fcz	Poser Face
.hd2 .hdz	Poser Hand
.anme	Anime Studio Document
.ani	Microsoft Animated Icon	icon
.asf	Streaming Audio/Video	icon
.avi	Microsoft Audio/Video Interleave	icon
.bvh	Biovision Hierarchical Data	icon
.qdp	Quidam Pose
.cfp	The SIMs Animation File	icon
.gif	Compuserve Animated Gif
.mov	Quick Time Movie	icon
.mpg .mpeg	Mpeg Video	icon
.wmv	Audio/Video Windows Media	icon
.seq	Renderware Sequence File	icon

Other

.phi	Poser Hierarchy File	icon
.pcf	Poser Coded Figure File	icon
.ds .dsa	Daz Studio Script Ascii
.dsb	Daz Studio Script Binary
.dse	Daz Studio Script Encrypted
.dsx	Daz Studio Script Xml
.mid	MIDI Sequence	icon
.wav	Microsoft Windows Wave	icon
.mp3	Mpeg Audio Layer	icon
.rar	Rar Archive File
.zip	Zip Archive File
.cbr .cbz	Comic Book Archive
.txt	Text File	icon
.htm .html	HTML Document	icon
.far	The SIMs File Archive	icon