In the accessories articles thread, I started to write about cheap accessories with the lens cap clip. While this is a very useful tool, it is no lenspen.
Lenspen is the accessory one must have if they are a camera user. It is a super effective cleaning tool which can clean your lens as well as your LCD screen (if any). Not only is it practical, it is also very cheap, $8.99 on amazon by the time I am writing this article. There is a regular lenspen and several other shapes available.
You can watch the how-to video for a demonstration. I bought one several months ago and I am very satisfied with it. Don't hesitate!