What I do to keep up is to read the preprints at
http://xxx.lanl.gov. hep-th is where the string papers
get archived. I'm also subscribed to notification lists
for gr-qc and quant-ph (http://xxx.lanl.gov/help/subscribe
describes how). I have my 'reading list' and a few notes at
(Warning: The individual files there are not very readable,
and nothing in my website ever stays put for long.) I usually read the preprints themselves in PDF format, which is an option under "Other formats" on the Abstract pages.