It's better to do it manually - try to socialize w/ ppl. If you have good content on your website - ppl will want to see it.
hmm unless you have intention to spamify people you wouldnt think of this. this world is not about you only, its a community
no i dont want to spam i just want to get my posts out there so i can get some more traffic to my blog
There are automated spam bots available but they are not worth it as you will likely get your accounts banned. As stated above it's a much better idea to do it manually, however more time consuming it may be.
Yes i use imgmo.com for posting pictures on facebook, twitter, myspace. Fast, simple, unlimited, secure and free. http://www.imgmo.com
One thing you could do is join a few, e.g facebook and twitter and automate your posts so although you will make the posts you only make them to one and it automatically updates the other. Therefore not being so spammy but also saving time