The SpamVilla Recaptcha OCR is probably the best known one and was the first available.
It has a high success rate of about 70%. It can even solve the blobby captcha type but of course with a lower success rate.
On the latest update (2014-09-26), they will also solve any other captcha baside Recaptcha and text captchas (questions like "What color is the sky?") using the decaptcha API.
- Price: 30 USD / Month (10 Thread, 2 PCs) - 150 USD / Month (100 Threads, 6PCs)
- Access: Via decaptcha API (tool available from them)
- Success Rate: 70% on photo captcha, 50% on normal captcha, 30% on blobby one