a.k.a the 'Autologgerinnerer'
This is super simple and not super secure. But hey, it's probably more secure than writing the details on a post-it note and sticking that to your monitor, eh?
This is not an example of good code, but it works for me. It should survive mild-markup changes by the HSBC team. Inspired by Chris Roos and his attempts to bypass HSBC's painful login procedure programmatically.
The Gist at the bottom of the page is heavily commented to try to walk you through it. It's not pretty, but if I was going to use anything to access my Internet Banking I'd want to give it a read-over first.
Through the power of online collaboration, Chris Roos (see the gist below for the non-edited docs).
Get a copy of John Gruber's perl script to create bookmarklets (Chris copied it and created a gist)
$ git clone git://gist.github.com/316867.git make-bookmarklet
Get the bookmarklet
$ git clone git://gist.github.com/266260.git hsbc-bookmarklet
Add your hsbc credentials to hsbc-bookmarklet/hsbc_bookmarklet.js
$ cat hsbc-bookmarklet/hsbc_bookmarklet.js | perl make-bookmarklet/make-bookmarklet.pl
Create a html page with a link to the bookmarklet
$ ruby -e 'puts "HSBC Login"' > bookmarklet.html
Open the html page and drag it to your bookmarks bar
$ open bookmarklet.html
Press once to go to the login form, press again to enter your IB number and submit, press again to complete the second page of the login form.