I had a look at the VUFind Search Tool the other day. It was quite fun to do a simple search across all formats, whether books, online, maps, microform, or audio. The demonstration search just uses a small database of items, which is effective enough at showing how the application works.
Today I had a play with the National Library of Australia's VUFind Portal which was really fun. I entered my home town as a search and scrolled through the 6 pages of items in various formats. Mostly maps, dairy farming reports, church treatises and genealogy, as well as a bit of poetry by some people I actually know. How exciting. I could tell you the name of my home town, but then I would have to kill you ;)
I like the VUFind, Web 2.0 type searching that is available now. It's so comprehensive. I found it easy to navigate - there are not many clicks to get to where you are going. Subject headings lead to hits I might have missed. I really like the breakdown of items into format type, as well as the author/subject/series/publisher/geographical links, which help one head off on various searching tangents very easily.
If it also sorts between items that are available and not, it will be perfect!