This is a short list of some of the tools that I (and others) depend on when we're working at clients.
Snag-IT! Commercial ($49.95). (Windows & Mac) http://www.techsmith.com/snagit.html Excellent tool if you have to document graphically intensive tasks. Provides nice ways to highlight and circle captured images, also allows you to quickly capture just the active window (or a pre-defined region of the screen), dump multiple captures into a directory, and even sequentially name the files.
Toad Commercial ($955.00 and up). (Windows only) http://www.quest.com/toad/ For many developers and implementation consultants, Toad has a virtually religious following. It is an excellent SQL query/development tool and allows you to easilly save query results into Microsoft Excel format (which will keep Oracle Support plenty happy). [Full disclosure: Those of you that have worked with me in the past know that I don't use Toad (or TOra, or SQL Developer, for that matter) for a variety of reasons (which will be explained in a later posting).]
TOra Open Source (Free). (Windows, Mac, Linux, Solaris) http://torasql.com/about Has many of the same core features as Toad.
Oracle SQL Developer Commercial (Free-ish). (Windows, Linux, others). http://www.oracle.com/sqldeveloper Also has many of the same core features as Toad.
VirtualBox Open Source (Free). (Windows, Mac, Linux, Solaris) http://www.virtualbox.org Do you want to run a Virtual Macine on your laptop? Maybe you're running Windows 7 and need a copy of Windows XP and an old version of IE so that you can test things and support your users? What if you'd really rather be using Linux but still have to run some Windows software? VirtualBox provides an easy way to create and run a VM of another operating system. Literally run Linux in a Window! (Or even fullscreen).
SecureCRT Commercial ($139.99) (Windows, Mac, Linux) http://www.vandyke.com/products/securecrt/index.html This is a very nice ssh client. It works very well and has a very nice user interface. Unfortunately, it's fairly expensive. Other (free) choices (on Windows) include: PuTTY http://www.putty.org/, BitVise Tunnelier http://www.bitvise.com/tunnelier, OpenSSH for Windows http://sshwindows.sourceforge.net/, and Cygwin http://www.cygwin.com/. If you're on a Mac or Linux system (or running a copy of Linux in a Virtual Machine), then you already have a built-in ssh client.