Some of the examples of Creating Sequential workflows can be found at following links:

http://www.devx.com/webdev/Article/34032/0/page/1

http://blah.winsmarts.com/2007-8-SharePoint_2007_Workflows_-_Setting_up_your_environment.aspx

http://weblog.vb-tech.com/nick/archive/2007/02/25/2207.aspx