http://www.getharvest.com/
Expense reporting, time tracking and invoicing system. Starts from $12/mth for 1 user. $40/mth for 2-5 users. Pricey, but looks solid. Includes twitter based SMS/IM integration (neat). Feels quite ajaxy, nice design. Hat tip Jamie Cockburn.
http://www.thisispearl.com/
Pearl's pitch is appealing. Integrate all your web services into one clean package. Let pearl handle CRM, accounting, billing, etc, etc. Feels a bit out of date, trying to be all things to all people. Interesting nonetheless.
http://www.myintervals.com/
Intervals is an online time tracking / invoicing system like FreshBooks / CashBoard. The web site seems dull. SSL is only available on $100/mth+ packages. $20/mth covers up to 10 projects, 500Mb, unlimited users.
http://xpenser.com/
Fire and Forget Expense Tracking. Fire in your expenses via twitter / im / email / sms / voice / etc. Then slap them together into expenses claims and send them automatically. I think Henk recommended it. Looks good, very ajaxy.
http://www.getcashboard.com/
Online time tracking and invoicing tool like FreshBooks. Paid accounts from $12/mth, 7 projects, unlimited invoices, unbranded, online payments, pdf invoices. Looks good. Multi-currency support.
http://www.blinksale.com/home
Blinksale is an online invoicing service, similar to FreshBooks, but with less functionality. Free for 3 invoices / month, $12/mth for 50, $24 for 250 including PDF invoicing, $49 for 1'500 invoices. Oozes ajax / rails / design. Integrates with PayPal.
http://kmymoney2.sourceforge.net/index-home.html
KMyMoney is a KDE based, open source financial accounting package. The web site looks very basic / old school.
http://www.freshbooks.com/
FreshBooks is an online time tracking / invoicing system. It will generate invoices, accept payments via PayPal / Authorize.net / etc. It sends reminder emails and so on. Packages from $14 to $150 per month.