More constructively, what are you trying to accomplish? There are few goals that a press release will help you with. It may help with some vanity links in Google News if you search for your name, but that's about it. If you want press coverage or user attention, a press release is almost certainly not going to help.
More info:
Short emails, 2-4 sentences, to the right journalists will be much more effective.
Check out our primer on how to write emails to journalists: http://muckrack.com/daily/2013/11/21/how-to-write-email-subj...
And if you still don't believe us on press releases, read the article I wrote for the PRSA that questions the press release's value, and debunks that it will help with SEO or social: http://comprehension.prsa.org/?p=6202
The question you want to be asking is "Who should I submit this to?", not 'Where?'. Which writers, bloggers, journalists etc have shown relevant interest to your startup's sector or pain point in the past? Write to these people individually, thanking them for having shown such an interest (link to a great article they've written, especially if you read and enjoyed it at the time) and introducing yourself, your startup, and the newsworthy angle you have decided for in your release.
Keep the email punchy. And if you do get any kind of response, even if it's to decline to write you up, be ever so grateful and make it clear that you would be happy to provide expert opinion on this topic if they ever sought it in the future.
It lists both free and paid submission services. Are paid services worth it?
It can have some good uses if you can get them wanting to ask more which would hopefully lead to a story.
