In a previous post Polybore mentioned Aniboom as an online service for producing animated GIFs. http://polybore.blogspot.com/2008/07/using-aniboomcom-to-make-your-own.html
Worth considering as an alternative is gifninja http://www.gifninja.com/
Gifninja is an online tool like aniboom. The main difference/ advantage is that you can upload your own images or, as Polybore has done, your own video file. 5 image limit for .jpeg or for video .wmv or .asf 4 of video seconds max.
Polybore tried it out by uploading a section of an ident video for Polybore’s sister blog watchblogvideos.com
The resulting gif has turned out pretty good you can compare it against the video before it was converted by clicking here. http://www.watchblogvideos.com/2008/10/new-watchblogvideos-ident-v20.html
If you need a gif then gifninja is well worth checking out.