I know a recordset object should be named rstName, but don't know all about variant naming specifications. I looked for it on MSDN for a long time, but couldn't find it.
A common prefix is vnt, but I tend to not use that. When I'm using Variants in VB, it's often to hold date/time values, so in that case, I'll prefix the variable with dat. The specific prefix really isn't that important as long as you're consistent in your naming.