Below is a list of Online bookkeeping programs. I have used them all and my comments are below each link.
Xero is my personal favorite. I have my own practice accounts in Xero. Its reliable, its easy to use and it integrates with a lot of other SAAS applications from CRM packages like Sales force to POS systems.
Kashflow Just like Xero, Kashflow is beautifully simple to use. Based in the UK Kashflow is slightly easier for UK based businesses in terms of VAT reporting.
Outright Unlike the other packages Outright is completely free. It is very much US focused and only supports dollars.