This looks like a very useful source that has both transliteration and translation of Sumerian texts. It is well sourced also, allowing one to easily find the published source.
This has a small number of translated documents.
Catalog of thousands of cuneiform tablets with photographs, line art, and transcription.
Lexical texts and lists are brought together from many periods here.
Autograph of the code of Hammurabi. Great for practicing old Babylonian lapidary cuneiform.
This is the standard lexicon for Sumerian, and its references are linked with the CDLI, ETCSL, and DCCLT. One can also search in Akkadian for the corresponding Sumerian word.
This is a handy resource for a quick look up.
The PDF's of all the published volumes of the CAD are available and searchable. This is a very hand reference, and more useful perhaps than the printed version.