You can receive subject alerts and new publication alerts as RSS Feeds. RSS (or Rich Site Summary) Feeds allow you to stay on top of frequenetly published information. The feed provides an overview of new content, and is available from databases, individual journal titles, and publishers. You can view your selected feed(s) by email, or using an RSS Feed aggregator like FeedReader.
Medworm is an excellent resource for finding news feeds by topic in Medicine.
Subscribing to RSS feeds from databases can be tricky, so the following help pages should make it a bit easier.
Usually you do not need to create an account for RSS feeds. Search for journal titles at these publisher websites. On each journal's home page, look for the RSS feed symbol to subscribe.
Before setting up email alerts in PubMed, you must sign up for a free account. www.ncbi.nlm.nih.gov/account/
RSS feeds do not require an account.
Information on creating email alerts and RSS feeds can be found on this help page.