Freeware 3Gp converter

Now MovieToolbox 3gp converter  - freeware. You can download and use it without any limitations.
www.movietoolbox.com/3gp-converter.html

Movietoolbox video joiner

Now Video Joiner can join the MP4 video format.

Movie toolbox Video Joiner can help you join multiple AVI, MPEG (MPG), MP4,  RM, (Real Media) or WMV/ASF (Window Media) files into one large video file. You can add an unlimited number of movie files as you like to the list. With just a few mouse clicks, you can enjoy your movie clips without interruption.
Video Joiner allows set the parameters of the output file: picture size, codecs, bitrates.
http://movietoolbox.com/joiner.html