A blog article from Localytics, Android Not As Fragmented as Many Think, lists most popular Android sizes and resolutions:
Another concern for Android developers is screen size and resolution. Of all app usage analyzed for this study, 41% of all sessions came from Android devices with 4.3 inch screens, by far the most popular size. 4 inch screens accounted for 22% of sessions, 3.2 inch screens for 11%, and 3.7 inch screens contributed 9%.
Resolutions were even less fragmented, however, with the most widely-seen screen resolution – 800 x 480 pixels – contributing 62% of the study’s sessions. The next most popular screen resolutions were 480 x 320 (14%), 960 x 540 (6%), 480 x 854 (5%) and 320 x 240 (5%).
Please note these statistics are from February 2012, which might be outdated today. Also, please always keep in mind that your app might be used under the inch sizes and resolutions not listed in this article.
EDIT: You should also be aware that there are Android "tablets" with large resolutions. The following quote is from the same article I mentioned:
Screen resolution and size are actually even less fragmented than handsets – 74% of Android tablet usage takes place on 7 inch devices with 1024 x 600 resolution. 22% are 10.1 inch devices with 1280 x 800 resolutions, so by taking into account two screen size/resolution combinations, developers should be able to easily reach nearly all of the Android tablet market.