Recently an app was released that allowed N9 users to add a logo to their N9's lock screens. As a person who loves customisation and phones with sleeping displays this was instantly appealing to me.
The app is called LPMcustomizer by Nick Leppanen Larsson and is available here, along with instructions: http://www.my-meego.com/software/applications.php?fldAuto=406&faq=13
When creating your own logo's you need to choose your colours wisely as only certain colours will work when the screen is in low power sleep mode. Colours that work are black, white, red, green, blue, cyan, yellow and magenta. I've yet to notice a significant drop in battery life when using these logos but if you do you may want to try a simpler designs using less pixels or switch the logo off.
Below are some of my early efforts, anyone is welcome to download and use these. I'm also open to requests if anyone would like a logo modifying or creating for their lock screen.