Enzymes
The Enzymes wiki is being developed, but some great sites to go to until it is complete are:
ExploreEnz, which is a simple enzyme database based on the IUBMB enzyme list.
Expasy, which is another simple enzyme database also based on the IUBMB enzyme list.
IntEnz, which is another simple enzyme database also based on the IUBMB enzyme list.
IUBMB, which is the IUBMB website.
KEGG enzyme, which is the enzyme part of the KEGG site, a very large and useful site.
Brenda, which is a very fancy database describing details of enzymes and their pathways. Will be a real shame when this one disappears.
CAZY, which is a smaller database focused on enzymes involving carbohydrates.
ThYme, which is a smaller database focused on enzymes involving thioesters.
Orphan, which is a smaller database focused on orphan enzymes.
MMEB, which is a smaller database focused on mammalian metabolic enzymes.
These links will probably not last long so get as much as you can from them before they disappear.