Representative Expression

1. You can submit your ATOM file which Google suggests but this has a few pitfals.
   In order to make good use of this method you have to make sure you ATOM file, or more specifically your feed settings are set so that as many of your posts are included. Quite often the feed file only contains a portion of your sites content. (For example, my feed file does not contain all 2500 individual pages on my site, it contains the last weeks worth of posts - hardly a sitemap). Now you can change your settings to include as many links as possible, but then that might upset anybody who is subscribed to your site via your feedfile. Whereas once they were pulling an ATOM file of a few kilobytes, they could be now pulling a massive ATOM file down with all of your site links.
   Those are the two main problems I see with using the ATOM file method.
   
   
2. Now this is a sneaky method but in no way does it upset Google and if fact might help with many other search engines as well. I would go so far to say that this is more of a common sense approach than sneaky.
   You have an index page which is normally your start page. Now the chances of Google not knowing about your site is fairly remote, and even if that is found to be the case, you simply go to Googles submit URL page and give them the URL.
   This means that they will come crawl your site in the very near future. In normal site crawling behaviour, this will mean that your index page will be scanned and any links found will also be crawled. In the past Google would actually look for a link that says 'Check here for a Sitemap of this site". In fact in googles SEO hints and tips they still recommend that a good site will provide a page that contains a user readable sitemap to help your users navigate around your site. If this user site map is more than a 100 links then they recommend that you split up your user visable site map into several pages. They will actively look for a user sitemap on your site because it makes their life easier to start from here rather than have to crawl your site to work out where everything is.
   This is actually where the Google Sitemap was born, all they did was create an XML format to make the process easier (rather than have a billion different formats floating around on the various websites).

• So even though we cannot upload our sitemap, we can still create one.
• We can upload it to a file server somewhere (a freebie webstorage type site, some friend who has space and bandwidth or similar).
• We then include a link to this sitemap file on our index page (via our template).

Now when google scan our site they will find the link to the sitemap, find the sitemap file and hopefully crawl its contents.
We can even place links to sitemaps of different formats. (You can have excel (csv), text (csv), Yahoo flavoured sitemap files, and many others).
One would hope that google would ignore all others and go for the Google flavoured one. So yes you can use Google Sitemaps if you are a blogspot user, but you have to make changes to your ATOM file (feed settings) that may make that file unusable for your readers or simply not contain any content of any real use.
I am yet to work out if is beneficial to do both (1) and (2), but don't know if Google would then not bother to further crawl your site if they already have your ATOM File. (Again, you would hope that your index page would be contained as a link in the ATOM file, which would in turn contain a link to the externally hosted sitemap file, which ulitmately would still get indexed by Google).
I would still like to think that at some point in time, Google would allow Blogspot users to upload, or better still, they would have a tool attached to the Blogspot user interface that allows you to create a sitemap file and then a button to tell them that you have generated one.
When you think that it is google that owns Blogspot, you would hope that they would allow you to host one simple file that would make their own lifes easier.
But then that brings up the point that Blogspot is actually hosted on their own machines anyway, and the simplest way for them to crawl ALL blogspot servers would be as simple as doing "ls -a or dir to all you windows people". Your site is on their machine, you'd think they'd know whats on their own machines. After all, the purpose of google sitemap is to tell them of sites and site content they don't know about !