I'm using GIMP to make the opening graphics, AbiWord to write the script, Audacity to record and edit the audio, CamStudio to capture the video (using the CamStudio lossless codec), Virtualdub to edit the video (using the CamStudio lossless codec) and to combine the opening graphics, audio and video, HandBrake to convert the AVI file to an MP4 and Aegisub to make the subtitles (I copy and paste from the original script and adjust the timing using the MP4 played as a guide in Aegisub and then export it as an SRT file).
I used to use Subtitle Workshop, but it isn't an active program now. It still works, but Aegisub is a lot like it, is cross platform and is still active.
I like including subtitle files in case a word gets clipped (or I mumble or something), for the hearing impaired and for conversion into other languages.
Hope that helps, Rodney.