I'm not a huge fan of the catalog and search at Ancestry.com, of which I am a member. If there is a database I've used there before and I want to find again, I usually search for it on Google.
In the Google search box:
- ancestry.com missouri marriage index
- ancestry.com iowa state census
Works wonders to get to those things I know I've used before, but am too lazy to create a big 'ol set of bookmarks for.