Some PSP video conversion tools are free and now I share what I have used

The Sony PlayStation Portable (Sony PSP) has become a very popular handheld game platform.  It is designed for gaming and viewing movies.  All the major film studios including Disney, Warner Brothers, Paramount and Sony Pictures have published movies specifically for the Sony PSP.   
         
The large handheld display combined with very good audio quality makes the Sony PSP an excellent choice when viewing movies on the go.   
     
The Sony PSP can play many different audio file formats, including the most popular two—MP3 and WMA. Video files for your Sony PSP need to be in a MPEG-4 format. Sony uses a slightly altered version of the MPEG-4 format which includes its own header information.
     
It is easy to transfer home movies or videos from your camcorder or even to show that you've recorded on your Media Center PC to your Sony PSP.  Some programs like Pavtube Video

Converter can convert and transfer video files from your PC to the Sony PSP, and the Pavtube DVD Ripper can perfectly help you rip the DVD to PSP.

There are some guides may help you quickly!!

How to put video on PSP - guide of using Pavtube Video to PSP Converter, PSP video format.
HOW-TO: Get videos and DVDs onto your Sony PlayStation Portable (PSP) for free - Engadget

More tools:

Convert video file to PSP: free tools and share tools!

Free:
PSP Video 9: PSP Video 9 - Free PSP Video Converter

Apex Free PSP Video Converter:
Download Apex Free PSP Video Converter 6.45 - The powerful features will make this application an execellent powerful video conversion solution on personal computer. - Softpedia

PSP Video Express 1.0
PSP Video Express reviews and free downloads

For DVD:

DVD Decrypter:DVD Decrypter v3.5.4.0 (freeware)
Free DVD Ripper: Download Free DVD Ripper - Freeware Download List
Pavtube DVD ripper: Best DVD ripping software, rip DVD to all format of video - Pavtube DVD Ripper, which is very easy for beginners，and support to convert directly to PSP.

Hanbrake: HandBrake it is easy to convert to iPod.
DVDshrink dvdshrink.org: FREE Backup Solution for your DVD movies!
DVDFab HD Decrypter Fastest DVD Copy Software | Best DVD Decrypter from DVDFab ; some functions are free.

Tips:

File Naming Convention

When storing video on the card a strange file naming convention is used. All video files and thumbnails need to be stored in a folder called: /MP_ROOT/100MNV01.

Each video in this folder is represented by a data file and a thumbnail file called: M4V00001.MP4 and M4V00001.THM. The 00001 component of the file name is incremented for multiple videos.

The thumbnails are simple 160x120 JPEG images stored with the .THM extension. Note that the title of the video is stored in the header of the file.

MOD Converter is a powerful MOD video converter which can convert MOD to AVI, MPG, MPEG, WMV and to other video format, such as MPEG-1, MPEG-2, ASF, DivX, XviD, MP4, VCD, SVCD, DVD-Video, VOB, DAT, RM, RMVB, MOV, QT, M4V, 3GP and so on. Batch conversion supported, you can add several .MOD files once a time. High MOD convert output video quality in the video aspect of 4:3 and 16:9. all encoders/codec are built-in and any supported conversion can be done once you downloading the software .
TOD Converter is a powerful TOD File Converter for windows user to perfectly convert TOD files to other popular video formats including AVI, MPG, MPEG1, MPEG2, WMV, ASF, DivX, XviD, MP4, VCD, SVCD, DVD-Video, VOB, etc. The TOD Video Converter also can convert AVI, MKV, MPV, MOD, TS, Mp4, M4V, MPG, MPEG, VOB files to other video format.The TOD Converter also provides powerful edit functions. The TOD Converter allows users to trim the added files, crop the files, adjust output video quality, adjust 4:3 or 16:9 video aspect, etc. Merge files into one is also permitted.

YouTube Video Converter is the most powerful YouTube assistant software in market today. The YouTube FLV Converter can download YouTube videos unlimited simultaneously (a real time saver!); Automatically name the downloaded video the same as the YouTube title; Convert YouTube videos to various video formats, including avi, DivX, XviD, rm, rmvb, MOV, MPEG, MPEG4 AVC, H.264 and WMV, VOB; VCD, SVCD and DVD Format .mpg; Convert download YouTube videos to a format compatible with your favorite portable device, including iPod Video, iPod Touch, iPod Nano, iPhone, Zune, PSP, PDA, Apple TV, as well as video capable MP3 players, 3GP mobile phones, and Pocket PC.
 
The FLV Editor is an idea solution to edit the FLV files without changing the FLV format. With the FLV Editor, we can clip the video, crop the video, merge the selected FLV files into one, add watermark on the FLV file, add subtitle, customize the video effect, etc. Moreover, the FLV Editor allows us to trim one selected file into several segments and output one FLV video with several output formats. (you can click the above related links to directly reach the related edit description or refer the left navigation)
 
The DVD to iPod Mac Software also can convert DVD to other popular video formats like: FLV, MPEG1, MPEG2, MP4, 3GP, 3G2, MOV, AVI, MPEG TS/TP (for HD Video), etc. With the DVD to iPod converter for Mac Software, you can freely enjoy your favorite DVD on video iPod, on iPod touch, iPod Video, iPhone, Apple TV, PSP, PS3, Youtube (web), Creative Zen, iRiver PMP, Archos, various video mobile phones and many other digital video and audio players.

Apple TV Converter for Mac is a popular and powerful video to Apple TV conversion software on Mac OS (including Mac OS X 10.5 Leopard).
 
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iPod Converter Mac enables you to convert all popular Video files to iPod Video. This professional iPod Converter Mac is the perfect solution for Mac Intel and Mac Power PC users to convert Movies and Video to iPod on Mac OS X. (including Mac OS X 10.5 Leopard).
iPod to Mac Transfer is perfect and powerful iPod transfer for Mac software. It offers iPod to Mac transfer of music, photo, video, movie, podcast and TV program. Moreover, iPod to iTunes, and Mac to iPod transfer are also supported.
FLV Converter for Mac is a powerful FLV converter Mac software which can convert FLV video files to all popular video formats and convert FLV to popular audio formats for Mac OS X users. FLV Converter Mac OS X softwrare supports all video popular formats indcluding FLV, MPG, MPEG1, MPEG2, MP4, 3GP, 3G2, MOV, AVI, Mpeg TS/TP (for HD Video), etc. FLV Converter for Mac can also convert FLV to MP3, WAV, OGG, 3GP, AAC and M4A, AC3, APE, etc audio.
iPhone Converter for Mac enables you to easily convert all popular Audio and Video files, such as AVI, MPEG, WMV, MP4, VOB, AAC, AC3, MP3, to the formats supported by iPhone, wide screen iPhone, and iPod Video and Audio including MP4, H.264, M4A, MP3 etc.

DRM removal is developed to help you convert DRM protected media, like DRM protected music and DRM protected movies and remove the DRM protection to enjoy them freely. This DRM removal can not only remove DRM protection, but also convert all common unprotected formats, convert DRM video, convert DRM music, including: WMA, WAV, WMV, M4A, M4P, M4V, M4B, 3GP, AVI, ASF, MP4, MOV, FLV, MP3, AC3, OGG, APE, etc. Innovative record-by-play resolution to remove DRM legally from media files, return you full user rights.