Sorry for being uninformative there, I realize I should have provided examples of what I'm having at the moment.
In the core, the application is similar to Tumblr in terms of how it manages content: there are articles, bookmarks, photos and quotes. Each entry has its own date and tags, but different meta data depending on its type: articles have title and body, bookmarks have URLs and description (which is actually a reblog or a reply to what the original URL author wrote), photos have an image and an additional description field and so on. I don't post often - the average is 4 to 5 entries on a monthly level, so filtering by day is useless here, but filtering by month could have its advantage in case I (or anybody else) was looking for a particular entry posted in, say, April 2009.
At first I thought of using something like you are using on your site with "/photos/photo-name", but it turned out that some pages look rather empty; for example, bookmarks with shorter description had lots of free space, while photos and articles managed to fill the page up. Then I came to an idea to use something like "/2011/04/#my_april_first_joke", which didn't produce free space on a page, but in return pages had titles like "Archive of April 2010", which I wasn't a fan of. Currently I'm thinking of sticking with the first solution and just getting over the free space in pages (or writing longer descriptions hehe), but I fear there might be a better and more elegant solution and that I am missing it.
Another thing I am trying to solve regarding the URLs is browsing. All entries have tags that were added to them in the Chyrp era and they are preserved in the exported files, so I think it would be good to put them in good use and make browsing entries a bit easier (as I write on a lot of topics, different people may be interested in different things; one could want only the programming related entries, while another person might want only entries related to chemistry and physics). For tags, I thought the URLs could be in the form of "/tags/programming" (where visiting "/tags/" only would display a tag cloud). As for date based archives, I thought the URLs could be in format like "/archives/2011/04". There's an alternate idea to have something like "/browse/" where entries could be browsed using query strings, something like "/browse/?tag=programming" or "/browse/?date=2011-04".
As this is my first time I'm building a blogging application and as I don't know much about URLs (except when making static sites) and how site indexing works, I'd like to know which combinations would work best for a small blog like mine. Also, if there are any things to be aware of when providing various methods to browse content, please let me know.