Usability 
Buxfer Buxfer has been in the news lately as one of the first two sites to use Google Gears for Mobile. The other Gears Mobile powered site, online office suite Zoho, only works with Windows Mobile devices. Buxfer is a personal finance and payment service and it supports most phones with a a mobile site and an SMS interface. Of course, only WinMo phones get the advantage of the Buxfer's new offline mode because Google hasn't released Gears Mobile for other platforms yet.
The full web version of Buxfer, which started out a simple service for tracking debts between friends and housemates, has grown into a full featured personal finance application supporting multiple accounts, import from Quicken, MS Money or .csv files, flexible search functions, analytics with graphing and budget management. You can also make payments from within Buxfer using Amazon's new PayPal like Amazon Payments service.
Buxfer's mobile web site is more limited than the full version but still useful. It lets you view account balances and transaction history, post an expense or payment transaction and check if your spending is within your budget. Buxfer can even send an SMS alert when you go over budget. You can sign up for the service on the phone too, something I think every mobile web service should allow.
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