I use a simple Excel spreadsheet. If you want it unmunge my email addy and
contact me direct.

I use "WeightWare" (http://www.weightware.com) from Shasta Software...but,
I'm the owner of the company, so that should come as no surprise :-).

Seriously, if you're interested in tracking your weight as it changes over
time, I think WeightWare is a very good tool.  Each day you weigh in, it
will calculate your "moving average weight", and your 30-day "weight trend",
using statistical analysis (we do the math, so you don't have to). "Frequent
weighing" has been identified by the National Weight Control Registry
project as one of the key behaviors associated with long term weight loss
success, and WeightWare can help by showing exactly how your weight is
changing (it can also give you advanced warning when your weight loss is
about to get off track).

WeightWare comes with a bunch of built-in weight analysis tools and graphs,
and it also tracks your exercise activities, and estimates how many calories
you've burned while exercising.  It's been designed from the ground up to be
easy to use, and it stores your personal information securely on your own
computer.

You can download a free, fully functional, 30-day trial version from the
website to see if it meets your needs.  If you have any questions about the
software, you can post them here, or send me an email (garyg at
shastasoftware dot com).

http://www.FitDay.com

I should get a commission, but, as always, I have no connection to Fitday,
except as a download customer.

I use the online version of FitDay.

http://www.fitday.com

There's also a software version, but you can't transfer data from one
to the other, which is why I stuck with the online version.