GPS Tracking recommandation

I like to tag my picture when I post them on flickr and I particularly love to geotag them - I think it's nice to be able to locate an area seen on a picture so you can visit it yourself at some point.
My workflow is pretty straight for now as I shoot in RAW, and import the raw files into Lightroom to develop them. I then upload them on flickr and use either the provided map, or tools like maps.yuan.cc (which permits using google maps instead of the one provided by yahoo.). This has three flaws , the first one is that I only geotag pictures that I upload on flickr, the information is only kept on flickr , so the day they die or the day I decide to move away from them my information is lost (well no - i can doanload a kml file and use it with google earth, but it would be a pain to regain that information).
What I would like is to geotag all my pictures, so either I find a GPS that directly plug-ins the camera and tags the pictures when I shoot (and I don't know of any solution to achieve this), the other one is to carry a GPS with me and then based on time stamps tag the RAW files by altering the EXIF data. The data matching seems to be easy to do.
My solve issue is finding the appropriate GPS hardware that will let me tracks my move. I am completely clueless on what my needs are - what I tend to do is go out for the day (maximum 10 hours) and shoot. Anyone willing to give me a recommendation on what piece of hardware I should buy ?