I've been freelancing for a few years now, and have always used a plain text file (or a spreadsheet if I'm feeling industrious). I've tried a few time trackers over the years but always end up forgetting to pause or start it back up, and end up having to do it all manually anyway.
So then there's the second part - how do you invoice clients? Personally I've just used excel templates and my clients have been happy paying with dwolla.com after the initial setup. How much in fees do you end up paying with other providers? Do any particular features make it worth it?
(full disclosure: I'm building a nearly fully automated time tracking and invoicing app which works great with my workflows, so I'm trying to get a sense of whether other freelancers have the same pain points I do and/or if it could work if I productized it...) Thanks!