You can clear the DNS cache on a Mac by using these commands (depending on the version of OSX you're running):
It is possible to have multiple iPhoto libraries, and not just one. To create a new library, hold down the Option (⌥) key while starting iPhoto. This will prompt you to create a new library or open an existing one.
Alternatively, you can also use iPhoto Buddy, which allows you to easily select libraries from a nice GUI.
Currently, the official Avast for Mac Edition available for download is still at version 2.74, released somewhere in 2007.
This version still has many annoyances and bugs that have not yet been resolved (one of these issues is the ability to run automatically in the background, without the main window popping up at start up each time).
Luckily, the Avast Forum has a post, providing a new release candidate is available for download for some time now. The build is also a bit outdated but has at least many fixes that aren't present in the official release.
The direct download link is: http://public.avast.com/~cimbal/avast.3.11.zip.
Wine now also has precompiled binaries available. Together with WineBottler (an application to prepare and pack Windows applications for redistribution with Wine), it is available here: http://winebottler.kronenberg.org/.
Wine is an application which allows to run Windows application on linux, BSD or Mac OSX. Rather than full emulation, it acts as a compatibility layer between the application and the OS.
Wine is not entirely foolproof just yet; there is still much to be done, but with each passing release, more and more applications are getting supported.
A friend of mine had this problem with her camera storage thingy. If you're a MacOSX user, you might want to read up on the symptoms and solution on her blog.
Extra thanks go to Heidi for this.