Over the last decade, software as a service (SaaS) has taken the computing world by storm. By being able to deploy software over the web, people no longer have to download bulky software packages and it’s given businesses a lot more flexibility. Today, SaaS is used to power a wide variety of business applications: sales force automation, CRM, document management, financials and of course Chargify.

In honor of SaaS flexibility and the recent release of the iPhone 4, we review some of today’s best SaaS apps for the iPhone and iPad:

Salesforce.com Mobile

Long one of the market leaders in customer relationship management, Salesforce.com also offers an iPhone app that can perform most of the important tasks of the full, web-based service. Salesforce.com Mobile (which also works on the iPad) is a robust application which allows sales teams and managers to track progress toward targets or quotas, record the status of various deals and proposals, store contact information for key decision-makers, view closed sales to date and more.

Whether you are a small business owner or a corporate sales manager, Salesforce.com Mobile can help you manage the entire sales process.

NetSuite for iPhone

Another leading business management SaaS app comes from NetSuite. Using NetSuite For iPhone, businesspeople can “access role-based NetSuite dashboards, including key performance indicators (KPIs), report snapshots, trend graphs, reminders and more.” The app also provides tailored access to key contacts and marketing campaigns, as well as up-to-the-minute data pertaining to opportunities, quotes, orders, purchase histories and other critical aspects of your business dealings.

NetSuite calendars and task lists can also be managed using the iPhone app.

iMaximo SightMax SaaS Live Chat

iMaximo SightMax is “the first and only business website live chat and real-time visitor monitoring application” for iPhones. This is a critical need of any business owner who utilizes real-time chat on their websites or sales pages, as you never know when the next big customer will visit with a pressing question or concern.

With SightMax, you can be there to answer – whether you’re at the office, on the golf course, or on the beach during a well-deserved vacation. In addition to answering live chat requests on your iPhone, SightMax lets you initiate chats with visitors and supervise live chats that your staff is engaged in.

Yendo

Yendo is the top choice for iPhone-based SaaS accounting software. Designed with on-the-go use in mind, the Yendo iPhone app is a breeze to use and offers real-time snapshots of your company’s monthly financial performance. Don’t waste time or eyesight hunched over your desk and squinting at stacks of columnar pads.

Instead, let Yendo make sense of sales and purchase data in easy-to-understand charts, whenever you feel the need to examine them. Yendo also helps keep track of which customers owe your company money, how much they owe, and by which date(s) they have agreed to pay.

Quicken For iPhone

Quicken is the essential money management tool for iPhone and iPad users. Using the free app, you can “see your bank, credit card, loans and other accounts all in one place, so you know exactly where your money is going.” If you already use a Quicken Online account, great – the iPhone app synchronizes with it automatically.

The Paycheck Forecaster feature also comes in handy by showing users how much money they have left alongside what bills are coming due (eliminating all confusion about what you can and cannot spend on other purchases.) Plus, with the Quicken iPhone app’s ATM locator, you’ll never be stuck chasing down ATM machines in strange areas again.