I’ve run into a bit of a wall doing three things with this blog, namely upgrading to WordPress 3.0, configuring and updating sitemap.xml, and exporting my posts (a necessary part of upgrading and migrating one’s blog).
All three of these memory intensive activities ran about against the PHP settings of my host – 1and1. I’ve by and large been happy with 1and1 – mainly due to cost – but it appears that their limitations are approaching a level where they may no longer be a viable hosting choice for hobbyist website builders.

The specific issue is that 1and1 limits their basic accounts to just 30MB of PHP memory usage. Exporting several thousand blog posts and updating a large sitemap simply consumers too much mempory, consequently, the jobs never run.
After attempting various fixes – changing wp-config and wp-settings as well as adding memory limits to .htaccess and creating php.ini in several directories – proved to be fruitless.
My solution – short of migrating my blog and changing hosts – was to disable every single plugin except the barest of necessities and THEN run either export (or import) or Google Sitemap. Once those tasks are done, you can re-enable plugins.
Along those lines, I went through my plugins and themes and examined what plugins or widgets were necessitating a database call. At some point in the near future, I will hard code those features (comment policy, Creative Commons license, Statcounter code, etc.) directly into the theme as opposed to using a plugin or widget. I was also running some plugins that are effectively obsolete thanks to new features in subsequent versions of WordPress. As such, I have decreased the plugin footprint of this humble blog from near-50 plugins down to a more manageable 32, with at least a few more destined for deactivation.