Freebase is a database that has all kinds of data in it and an API. Because it’s an open database, anyone can enter new data in Freebase. An example page in the Freebase db looks pretty similar to a Wikipedia page. When you enter new data, the app can make suggestions about content. The topics in Freebase are organized by type, and you can connect pages with links, semantic tagging.
Visit freebase.com . You will find a Search Textbox on the top right upper corner.
Type a letter in that provided textbox and wait . It will give possible combinations and if you hover on any suggestion … it will open a very small window which contains information regarding that suggestion ( and it specifies the category and a short description with an image(if exists)). The best part is you can get the classification of the suggestion also.
How I used in my project?
I have a textbox and a search textbox. As on typing in the textbox suggestions for the end user should come with possible combinations ie Autocomplete feature.
Then from google open projects I found a useful link. http://code.google.com/p/freebase-suggest/
Download jquery.freebase.suggest-0.3 zip file
Then that suggest_demo_with_minitopic.html will provide the autocomplete feature.
Really sounds great with Semantic web.
In Freebase you can get "Advanced Search" and Query Builder applications which will really the change the way you search in net.