The overabundance of conferences makes it absolutely necessary to prune and submit selectively. Based on 2007 Australian Ranking of ICT Conferences based on data collected over five years and Computer Science Conference Ranking which employs the Estimated Impact of Conference (EIC), I have listed only the places relevant to robotics and/or machine learning. Based on | , , , I have tried to distill all available ranking information.
|Conference||EIC||Australian Ranking||Acceptance Rate in Year||Cite Scholar||CiteSeer Rank (2008)|
|AAAI: American Association for AI National Conference||0.99||A+||24.2% in 2008||3.13||99|
|NIPS: Neural Information Processing Systems||0.98||A+||24% in 2006||2.69||45|
|KDD: Knowledge Discovery and Data Mining||0.97||A+||23% in 2006||7.05||119|
|IJCAI: Intl Joint Conf on AI||0.96||A+||18% in 2005||2.66||61|
|ICML: Intl Conf on Machine Learning||0.95||A+||27% in 2008||6.09||38|
|UAI: Conference on Uncertainty in AI||0.91||A+||32% in 2006||139|
|AAMAS: Intl Conf on Autonomous Agents and Multi-Agent Systems||0.76||A+||36% in 2008||3.12||361|
|ECML: European Conf on Machine Learning||0.76||A||19.70% in 2005||134|
|ICPR: Intl Conf on Pattern Recognition||0.76||A||62.8% in 2006||0.81|
|ECAI: European Conf on AI||0.76||A||26% in 2006||1.38||531|
|ICDM: IEEE International Conference on Data Mining||0.73||A+||19% in 2007||2.3||423|
|PKDD: Principles of Data Mining and Knowledge Discovery||0.62||A||393|
|ICRA: IEEE Intl Conf on Robotics and Automation||0.60||B||38% in 2006||1.48||372|
|ICONIP: Intl Conf on Neural Information Processing||0.56||A||33% in 2006|
|R:SS: Robotics: Science & Systems||0.53||A+||17% in 2010||48|
|SDM: SIAM Intl Conference on Data Mining||0.51||A||16% in 2006||370|
|IROS: International Conference on Intelligent Robot Systems||<0.5||B||58.2% in 2010||0.79|
The CiteSeerX Rank of 100 or smaller is common for top conferences.
Note that Microsoft also suplies interesting data on some of these venues.
Unfortunately, these statistics are NOT as solid as the ones of the jounal impact factors. However, a robotics or machine learning conference which is not on this list will most likely not be considered "refereed publications" when you apply for jobs.
An engine that may become helpful in the future is http://citescholar.org/. Unfortunately, they are still missing top conferences such as R:SS.