Another .seq to .fa converter, except this one dumps all the data into a single .fa file with multiple entries.

seqs2fa.py

import os
import os.path

def main():
    outdir = 'FASTA'
    if not os.path.isdir(outdir):
        os.mkdir(outdir)
    with open(os.path.join(outdir, 'bundled_seqs.fa'), 'w') as output:
        for s in os.listdir(os.getcwd()):
            r, e = os.path.splitext(s)
            if e.lower() == '.seq':
                newfile = '{0}.fa'.format(r)
                with open(s, 'r') as inp:
                    output.write('>{0}\n'.format(r))
                    output.write(inp.read())
                    output.write('\n')

if __name__ == '__main__':
    main()