Boliven is a free patent search site that you may find useful. It covers several patent authorities (USPTO, EPO, PCT, JPO, KIPO) plus INPADOC and includes patent file histories and assignments. It also has some graphical analytics (top assignees, top examiners, etc) that you may find interesting along with data export, bulk PDF downloads, and more.
They have also just released a set of free Boliven Web Services that may be of particular interest to you if you are a blogger. Included are a nifty patent drawings scrollbox widget, patent search RSS feeds, a handy patent search box widget (see below Tools section in left sidebar), and more, all of which can be easily added to blog posts and sidebars.
To help kick off their new web services they are going to have drawings for a new Kindle DX and some Amazon gift certificates - open to bloggers in particular. To enter in the drawing, you will just need to register and use two or more of their widgets, feeds, or links on your site for one month or more.
Take a look here.