if (-e "/dev/random"){ .... } else { .... }

To generate a nice seed where you don't have /dev/random, you can do a checksum on your environment. Here are some sources of bits that are not random, but hard to reproduce:

• concatenate keys and values of %ENV{}
• process id, ppid
• current time
• process table
• disk statistics
• network interface report, especially if it can list counters
• inode number of $0, and arguments if any
• names of arguments, if any
• strings coming out of the memory allocator (allocate some references, stringify them)

Once you have a big string you can pipe it through a compression or cipher algorithm, just to distribute bits across 8bit space evenly, and use unpack to count the sum (see examples in perldoc).

/dev/random collects entropy from drivers, timers, and so forth, so essentially you're doing a cheap emulation of that.

If you get something nice, make a module out of it: Entropy::Gather::Win32 or something.