Phoshare allows you to export and synchronize your iPhoto library to a folder tree. It preserves both the original and modified image, your event and album organization, and applies your iPhoto titles, descriptions, keywords, face tags, face rectangles, places, and ratings to the IPTC/EXIF metadata of your images. You can export a full copy of your library, or just build a tree of linked images that require very little additional disk space. You can re-run phoshare at any time to synchronize any changes made in iPhoto to your export tree quickly. phoshare works well with file-system based photo management tools like Picasa, Adobe Bridge, or Windows Live Photo Gallery.
iPhoto is pretty slow on my old MacBook and while it might be perfectly awesome on a newer MacBook Pro, it is a real pain to use. The big advantage to using it is that it syncs with my iPhone perfectly (as you would expect) but iTunes does give you the option to sync specific folders with your iPhone so that might be an answer. iPhoto also integrates better with Facebook and Flickr than Picasa. Picasa has certain benefits over iPhoto like far better face recognition and is somewhat more lightweight than iPhoto.
My ideal is still to switch to Lightroom for all my photo needs but I don’t have the cash right now to cover the cost of that app so I am working with what I have. I imagine Phoshare would come in handy when I make my move to Lightroom, though.
Dan Warne published a really helpful blog post explaining how to export your iPhoto library for upload to services like Dropbox or S3 here. The same steps could be used to simply export a slightly smaller version of your main iPhoto library if you don’t need the full resolution.