There are quite a bit of these around (fully aware of that), but we're trying to make a step ahead. Think of Cronforce as online timesheets meets vacation/absence scheduling meets project cost management for SMBs/startups. Real time tracking and rich 3rd party integrations to complete the picture.
The focus right now is bundling the software with segmented apps (think Google Apps, Jira, Basecamp, SAP, Trello). We're heavily relying on the Jira integration as it seems a lot of users are keen on it:
http://cronforce.com/integrations/jira-time-tracking.html
Would be glad to have your opinion on what works and what could be better!