There are a couple of options available in Jabber for Windows. Firstly, if you have web pages, you can use protocol handlers to launch Jabber functions.
http://www.cisco.com/en/US/docs/voice_ip_comm/jabber/Windows/9_0_1/b_jabber_win_icg_chapter_01.html#JABW_TP_PF21EDAF_00You can then extend the Jabber functionality by adding extra tabs on the left (under call history, voicemails etc.). To do this, you basically embed HTML/CSS into the client. There is more information about "Custom Embedded Tabs" here:
http://www.cisco.com/en/US/docs/voice_ip_comm/jabber/Windows/9_0_1/b_jabber_win_icg_chapter_01011.html#JABW_RF_CDF3DF99_00 Hope that helps.