Here is a compilation of various useful resources (this page is still under construction!):

Linguisystems: This is a GREAT company, they provide excellent Speech/Language materials and many 'freebies'.  Here is a free chart for all speech and language milestones!!

SuperDuper Publications: Another GREAT company for Speech and Language materials, as well as many 'freebies'!
Check out their Handy Handouts!  All of them are free and there is a large variety of topics!

ConnectAbility: This is a site, FREE, that is similar to Boardmaker or Custom Boards.  It does not have as many images as Boardmaker/Custom Boards; however, it seems to have a nice selection of real images and clipart.  To use this, you will select how many pictures you wish to create.  You can then customize your 'board' by searching for pictures of words.  This is useful for creating vocabulary, articulation, and other language 'boards' for therapy or home practice. 
Website (or click on link above):