#1 This is a no-brainer. Google Apps for Business is simply fantastic! Create your own branded email account for business (powered by Gmail), share documents, calendar events, etc. Have total administrative control over the accounts and create as many users as you want with different user rights and privileges. Google Apps also supports tons of additional applications that you can install in a click.
#2 Freshbooks We love this app. FreshBooks lets you build your own branded billing system that you can connect with PayPal or your own Payment Gateway (Authorize.net, Beanstream, etc…). With FreshBooks you can also manage your expenses, add users and generate detailed reports of you earnings, expenses and clients. You’ll love this application even more when tax season rocks around again...
#3 Shoeboxed - amazingly convenient receipt management Hate managing paper receipts? Shoeboxed is what you need. Once you sign up, you can install their iPhone app that lets you “scan” & digitize your receipts. The app then sends the receipt electronically to your ShoeBoxed account. They also provide you with a personal email address that you can forward your online receipts to. Fantastic for keeping track of all your receipts and extracting reports at the end of the year for tax reports.
#4 Highrise - the foolproof way to capture and nurture every lead
Great Lead & Customer Management for Small Businesses - you can store every conversation, email, call, meeting, document, and deal you’ve ever had with a contact. You’ll always know who you talked to, what was said, and when to follow-up next. You can also create additional users, delegate tasks and much more.
#5 Constant Contacts
I've used a lot of different companies over the years to manage my email marketing and constant contacts is still my favorite company. Email Marketing is still the most powerful form of Online Marketing when done properly. Constant Contacts is user-friendly, powerful & cheap - you can schedule events, create auto-responder campaigns, and create opt-in boxes for your website with just a couple of clicks.