British Midland is winding down its operations as BA bought it back in April. You can still redeem BMI Diamond Club miles for Star Alliance flights excluding Lufthansa Group (Lufthansa, Swiss, Austrian and Brussels Airlines) until the end of May. As a matter of fact, I need to get last few redemption bookings in rather sooner than later.
BMI just emailed an offer to buy Diamond Club miles and they will throw in 20% extra. During the sale 24K BMI Diamond Club miles will set you back 255 GBP that is around $400. Note that there is no special link for this offer. It will show up automatically, when you go and buy the miles.
Later in the summer you can freely transfer BMI Diamond Club miles to British Airways Avios. You can think of this BMI offer as if you are buying Avios, if you happen to need more after beginning of July.
There are great bargains from Europe to burn BMI miles to places like Maldives that I wrote about, and for intra-Asia/Pacific C/F. You will pay hefty fuel surcharges, but the number of miles needed is much lower compared to other programs.