General Exegetical Links:
Preaching the Lectionary
http://www.amazon.com/Preaching-Lectionary-Word-Church-Today/dp/0814613519
Jerome Biblical Commentary: http://www.amazon.com/Preaching-Lectionary-Word-Church-Today/dp/0814613519
St. Paul Center for Biblical Theology http://www.salvationhistory.com/
http://www.rc.net/wcc/readings/index.html
http://www.crossroadsinitiative.com/library_category/38/Catholic_Bible_Study.html
http://phatcatholic.blogspot.com/2007/01/scripture-commentary-by-fr-william-g.html
http://www.catholic-pages.com/dir/commentary.asp
General Intercessions (Prayers of the Faithful)
Here are some general principles: http://dsjliturgy.blogspot.com/2004/09/10-principles-for-writing-general.html
Good examples: Pentecost: http://liturgy.slu.edu/PentecostB053109/ideas_other.html
Here's some interesting preaching blogs worth exploring:
http://www.catholicpreaching.com/
http://www.homilies.com/
http://deacbench.blogspot.com/2009/02/its-general-mediocrity-of-catholic.html
http://www.americamagazine.org/blog/blog.cfm?blog_id=1
http://www.op-stjoseph.org/blog/tags/Word_to_Life