Electronic Tables of Contents (eTOCs): You decide on the journals. The table of contents with full-text links will be delivered to you with the release of each new issue. This can also be done for multiple journals through Web of Knowledge using your free personal account.
PubMed's MyNCBI: PubMed personal account. You can specify that PubMed run previously saved searches. MyNCBI will deliver new articles from your searches to your email or an RSS reader.
Ovid Personal Account: Similar to PubMed's MyNCBI, but for the Ovid databases.