SkypeHistory is a project mainly written in Python, it's free.
Skype history exporter
This is Python script for export Skype chat history from many datafiles in one place to comfortable viewing and searching.
Usage: skh.py [options]
Options:
--version show program's version number and exit
-h, --help show this help message and exit
-i FILE, --input-file=FILE
Input file (multiple)
-l LIST, --list-file=LIST
File with list of input files (one by line)
-o DEST, --output-file=DEST
Output file name
-t TYPE, --type=TYPE Type of export [xml|txt|html|db]