File Synchronization on More than One Computer
Dropbox offers 2 GB of free storage space, synchronized on more than one computer. Sign up using this link and my space allocation will be increased: http://db.tt/ut436cI
Here are two programs that allow people to upload to your Dropbox, without accessing it: DROPitTOme is a free service that provides a url that you can give to others to upload files to your Dropbox account. File Stork allows you to make an individual file request by sending an email to someone, or to create a “stand alone” request which will allow you to post an upload link on your blog or website.
Password Management
Roboform keeps all your logins synced on multiple computers, and fills forms with a single click. You only need to remember one password and all the rest are stored in a secure file. I am an affiliate for RoboForm. For more information on Roboform, click here.
Electronic payments and gateways
Paypal offers free accounts for businesses and an easy and safe way to accept credit card payments via the internet.
Paypal business accounts offer powerful options for small businesses. I am an affiliate for this service.
Email Clients
Thunderbird.
FTP Support
FTP support using 
WinSCP and 
Filezilla.