Free online multimedia conversion tools

KickYouTube - http://kickyoutube.com
This website allows you to convert any Youtube videos into a number of formats, including stripping only the audio part in MP3 format. Just locate the desired Youtube video, choose the output format among many available choices, like FLV, HD, AVI, MP3, OGG, hit the green Go button in the right corner and let it work! Simple, friendly, powerful!
Media Converter - http://www.mediaconverter.org
Media Converter allows you to work with online Flash files as well your own files, which you can upload for conversion. The free usage is restricted to files no larger than 100MB, slower conversion process, lower resolution, and only up to five actions a day. The free service also works with fewer online websites, although break.com, dailymotion.com, facebook.com, metacafe.com, and youtube.com are included. The services comes with a pleasant interface and useful help.
ZamZar - http://zamzar.com
ZamZar is a tremendously useful and powerful online conversion service, which will work not only with a wide range of your media files, it will also work with many document types, compressed archives, CAD formats, and more. Media-wise, ZamZar works with MP3, RealMedia, FLAC, AAC, MP4, FLV, 3GP, QuickTime, and others. Unlike the other two services mentioned earlier, ZamZar does not work with Flash-streaming websites, but it supports a wider range of formats. No worries, download them using one of the other services, then convert with ZamZar!
ZamZar sends converted files to an email address. Registering for the premium service entitles you to a 100GB online storage, 1GB file limit size, secure transfer, and many other perks, but this does cost money. We will talk about ZamZar in the second part of this compilation, when we talk about document conversion services.
ConvertTube - http://convert.playtube.com
ConvertTube is a part of the PlayTube video blog. This service allows you to convert Youtube movies to a variety of video formats, like .mpg, .wmv, .mov, and .mp4, download the file in Flash (.flv) format or just strip the audio track and convert it to .wav, .mp3 and .3gp. ConvertTube is simple, but it does its job well.
movavi - http://online.movavi.com/
movavi online convert service offers a simple, clean 3-step interface and works with either URLs or uploaded files, limited to 100MB in size and no more than 10 min in length.
movavi offers a useful range of output formats and codecs, including .avi, .mov, .mpeg. .mp4, and .flv, encoded as Xvid, Mpeg-2, Mpeg-3, iPod and iPod 5G, iPhone, PSP, 3gp, and 3gp2. The service can also produce audio tracks. The service also allows you to merge files.
vixy.net - This service allows you convert Flash videos MPEG4 files.
ConvertDirect - Like vix, this service offers downloading Flash videos from popular websites, or converting them to a number of formats, including AVI, MOV, MPEG4, as well as audio only MP3 and AAC.
KeepVid - This site works with Youtube, Dailymotion, Metacafe, and other popular sites and allows you to download Flash files to your machine. Probably redundant if you're using Firefox with DownloadHelper, but quite useful for people using other browsers.
Media Convert - This site can do a lot; it supports a wide range of file formats, including not only audio, video and image, but also documents and archives and comes close to what ZamZar offers. The service also includes advanced settings, like splitting and merging videos and changing the bitrate.